I really need to invent some more concise way to do simple
error checks and logging.

Some versions of autotools seem to do this automatically because
these are dependencies of the gresources .c files.

* docs/users-guide/C/glom.xml: Rename this to index.docbook.
* docs/user-guide/Makefile.am: List the index.docbook and legal.xml
  files in HELP_FILES, not using HELP_EXTRA. This is
  what gnome-system-monitor does and it seems to fix the problem
  with unbuilt stamp files.

* data/ui/developer/box_formatting.glade:
  Arrange the Related Records choices in a grid, making the
  dialog wider, but less tall.
  Likewise, arrange the last two checkboxes horizontally instead
  of vertically.
* data/ui/developer/dialog_layout_field_properties.glade:
  Move the Formatting to the entire right-hand side of the dialog.
  This leaves ugly empty space at the left of the dialog,
  but it makes the dialog less high.

* glom/mode_dsign/fields/dialog_fielddefinition.[h|cc]:
* data/ui/developer/window_field_definition_edit.glade:
  Move the Default Formatting notebook tab into:
* glom/mode_design/fields/dialog_defaultformatting.[h|cc]:
* data/ui/developer/window_default_formatting.glade:

* glom/utility_widgets/adddel/adddel.[h|cc]:
  Add signal_user_requested_extra.
* glom/utility_widgets/adddel/adddel_withbuttons.[h|cc]:
  Add set_edit_button_label() and set_extra_button_label()
  and override show_all_vfunc() to not show the extra button if
  it has no label.

* glom/mode_design/fields/box_db_table_definition.[h|cc]:
  Use the new button to show the new dialog.

It's more friendly to older versions of intltool and it is overall
a good practice.

Mostly increasing the horizontal space between widgets from 6 to 12,
and increasing the vertical space between groups of widgets to 18.
See https://developer.gnome.org/hig-book/unstable/design-window.html.en#layout-dialogs

* data/ui/developer/*.glade: Remove parent GtkFrames and GtkAlignements
  if there is only one, because no grouping is necessary.
  This was probably necessary once because some older version of the
  GNOME theme did not show window titles for modal dialogs, but that
  does not seem to be the case anymore.

It's more friendly to older versions of intltool and it is overall
a good practice.

* data/ui/developer/window_relationships_overview.glade:
  Change this from GtkWindow to GtkApplicationWindow.
* mode_design/relationships_overview/window_relationships_overview.cc:
  Change the print and page-setup actions to be in the standard
  win. group.
* glom/frame_glom.cc: Add the window to the GtkApplication.
* glom/application.cc: on_startup() : Add a Ctrl P acelerator.

This is now a GtkWindow, rather than a GtkDialog, allowing us
to arrange things so that the menu is snugly against the edge.