* glom/utils_ui.h: dialog_run_with_help(): Add a templated version that uses
  the static glade_id member, to avoid repeating this in the source code.
* Several .cc files: Remove the ID parameter from most uses of
dialog_run_with_help().

  * glom/glade_utils.h: get_glade_widget_derived_with_warning():
  Don'te an ID. This requires the class to have a static glade_id member and
  glade_developer (bool) member, telling us what file and what ID to use.
  This associates the IDs and filenames with the class, instead of being in other files,
  to avoid duplication and to avoid using the wrong ones.
  This allows us to remove get_glade_developer_widget_derived_with_warning().
  * Many files: Use these new methods, to avoid mentioning glade IDs.
  * tests/test_glade_derived_instantiation.cc: Try to instantiate all the known
  derived glade dialogs.

* glom/glom_developer.glade:
* glom/glom.glade: Move dialog_choose_date to glom.glade.
* glom/mode_data/datawidget/datawidget.cc: on_button_choose_date():
Adapted.

Application: Forget the global instance when it has been deleted.

  * glom/application.cc: Destructor: reset the static instance to 0,
  to avoid anything from retrieving the pointer to the deleted object.

* glom/base_db.cc: offer_item_formatting(): Remove a useless use of
Gtk::Builder.

* glom/base_db.cc: :offer_notebook(): Fix a typo in the glade ID.
I'm working on code to prevent these kinds of errors, to apply when we branch.

  * glom/glom_developer.glade: dialog_groupby_secondary_fields: Rename a
  button to match what the class's constructor expects.

* glom/glom_developer.glade: (dialog_add_related_table) Remove frame,
fix spacings, align form elements in table.
* glom/mode_design/dialog_add_related_table.cc: Add window icon.

* glom/application.cc:
* glom/glom_developer.glade:
* glom/mode_design/script_library/dialog_script_library.cc:
* glom/mode_design/translation/window_translations.cc:
* glom/mode_design/users/dialog_groups_list.cc:
Translation dialog updates, set missing window icons.

* glom/frame_glom.cc: Set window icons.
* glom/glom_developer.glade: Update user dialogs.
* glom/mode_design/layout/dialog_layout.cc: Set window icons.
* glom/mode_design/users/dialog_groups_list.cc: Set window icons.

* glom/mode_data/box_data_details.cc:
* glom/mode_data/box_data_details.h:
Use HButtonBox instead of HBox.

* glom/utility_widgets/adddel/adddel_withbuttons.cc:
* glom/utility_widgets/adddel/adddel_withbuttons.h:
* glom/utility_widgets/db_adddel/db_adddel_withbuttons.cc:
* glom/utility_widgets/db_adddel/db_adddel_withbuttons.h:
Use ButtonBox instead of HBox.

* glom/utility_widgets/db_adddel/db_adddel_withbuttons.cc:
* glom/utility_widgets/db_adddel/db_adddel_withbuttons.h:
Use ButtonBox instead of HBox to make buttons homogenous. Also change
button order to match order used everywhere else (Add/Delete/Open).

* glom/utility_widgets/imageglom.[h|cc]: Move scale_keeping_ratio() to
glom/utils_ui.[h]cc] as Utils::image_scale_keeping_ratio().
* glom/utility_widgets/canvas/canvas_image_movable.cc:
* glom/utility_widgets/db_adddel/db_adddel.cc:
* glom/utility_widgets/flowtable_dnd.cc: Adapted.

  * glom/mode_data/datawidget/: Removed Glom suffixes from class names
  and filenames, and put classes in a DataWidgetChildren sub-namespace,
  to make it clearer where we occasionally use these outside of DataWidget.

  * glom/utility_widgets/datawidget.[h|cc]: Moved to glom/mode_data/datawidget/
  because it is only used by the data-mode flowtable.
	* glom/utility_widgets/buttonglom.[h|cc]
	* glom/utility_widgets/checkglom.[h|cc]
	* glom/utility_widgets/combo_as_radio_buttons.[h|cc]
	* glom/utility_widgets/combochoices.[h|cc]
	* glom/utility_widgets/combochoiceswithtreemodel.[h|cc]
	* glom/utility_widgets/comboentryglom.c[h|cc]
	* glom/utility_widgets/comboglom.[h|cc]
	* glom/utility_widgets/dialog_choose_date.[h|cc]
	* glom/utility_widgets/dialog_choose_id.[h|cc]
	* glom/utility_widgets/entryglom.[h|cc]
	* glom/utility_widgets/labelglom.[h|cc]
	* glom/utility_widgets/textviewglom.[h|cc]
	* glom/utility_widgets/placeholder-glom.[h|cc]: Also move these to
  glom/mode_data/datawidget because they are only used by DataWidget.
	* glom/utility_widgets/alignment_justified.[h|cc]:
	* glom/utility_widgets/table_columns.[h|cc]: Deleted these unused classes.
  * Makefile_glom.am: Adapted.

* glom/glom_developer.glade: Various dialog layout fixes.
* glom/mode_design/layout/layout_item_dialogs/dialog_imageobject.cc:
* glom/mode_design/layout/layout_item_dialogs/dialog_imageobject.h:
* glom/mode_design/layout/layout_item_dialogs/dialog_textobject.cc:
* glom/mode_design/layout/layout_item_dialogs/dialog_textobject.h:
Update box variable name and add window icons.

* glom/application.cc: Update copyright year in about dialog.

* glom/application.cc: on_document_load(): Add an extra call to
    document_history_add() after successfully saving from an example.

* glom/frame_glom.cc: Rename Quick Find to Quick Search and add
mneomnic.
* glom/glom.glade: Update find id dialog and remove frame.
* glom/utility_widgets/datawidget.cc: Add window icon to find id
dialog.

* glom/glom.glade: Spacing adjustments to make dialogs more HIG
compliant.

* glom/glom_developer.glade: Initial Password Dialog tweaks.
* glom/mode_design/dialog_initial_password.cc: Set window icon.

* glom/glom.glade: Import dialog tweaks.
* glom/import_csv/dialog_import_csv.cc: Add window icon, change title
order.

* glom/frame_glom.cc: Add window icons and fix capitalisation of
primary texts (dialog text uses sentence capitalisation).

* glom/glom.glade: Set a reasonable default size for the progress
dialog, that allows to read the title at least.

* glom/glom_developer.glade: Spacing and mnemonic adjustments/fixes,
remove frame label.
* glom/mode_design/layout/dialog_choose_field.cc: Add window icon.

* glom/dialog_progress_creating.cc: Add window icon.
* glom/glom.glade: Center dialog on parent window.

* glom/dialog_existing_or_new.cc: Also don't show error icon for
empty recent documents.

* glom/dialog_existing_or_new.cc: Fix typo and use of properties, don't
show error icon when no network sessions are available.
* glom/glom.glade: Hide label and icon, spacing adjustments.

* glom/application.cc: Don't show colon in application title when
table name is empty.

* glom/frame_glom.cc: No table warnings are not needed anymore
for menu items, so remove them.

* glom/utils_ui.cc: show_ok_dialog: Set window icon.

* glom/dialog_existing_or_new.cc: Set window icon.

* glom/application.cc: update_table_sensitive_ui: Function to set
sensitivity of menu items depending on whether a table is loaded.
init_menus: Add table sensitive menu items to a list.
* glom/application.h: Add list to hold table sensitive menu items.
* glom/frame_glom.cc: Call update_table_sensitive_ui when needed.

	* glom/application.cc: Use lower case for short prepositions.

	* glom/application.cc: Add missing mnemonics and change double
	mnemonics.

* glom/glom_document.dtd: data_layout_button: Allow this to have a
    formatting child node, because we now allow this in the UI and save this.

    * Makefile_tests.am
* tests/glade_toplevels_instantiation.cc: Added this code for an
    executable that will try to instantiate all GtkWindow and GtkDialog
    objects in a specified .glade file. It also checks that they are not
    visible by default.
* tests/test_glade_toplevels_instantiation.sh: Added a tests script,
    run during make check, to run this executable on all our .glade files.

    * glom/glom.glade, glom_developer.glom: Fix small problems found by the
    test, removing an empty textbuffer top-level object and making all
    top-level objects non-visible by default.