Fixed bug 4427 (Should not execute text files by default).

	Now it asks whether to run or display executable text files.
	Advanced users can set a new preference.

	* libnautilus-extensions/nautilus-stock-dialogs.h:
	* libnautilus-extensions/nautilus-stock-dialogs.c:
	(create_message_box): New bottleneck function, contains former
	guts of show_message_box but doesn't call gtk_widget_show.
	(show_message_box): Now just a simple wrapper for
	calling create_message_box and showing the result.
	(nautilus_show_info_dialog), (nautilus_show_warning_dialog),
	(nautilus_show_error_dialog), (nautilus_show_yes_no_dialog),
	(nautilus_show_error_dialog_with_details):
	Renamed to add verb "show" to names.
	(nautilus_run_simple_dialog): Renamed to add verb "run" to name.
	(nautilus_create_question_dialog): New public function, does
	not show the dialog yet so caller can add more buttons or
	whatever before showing.

	* libnautilus-extensions/nautilus-global-preferences.h:
	* libnautilus-extensions/nautilus-global-preferences.c:
	(global_preferences_install_descriptions),
	(global_preferences_install_defaults),
	(global_preferences_install_visibility),
	(global_preferences_create_dialog): Add new preference for
	what to do when an executable text file is activated. It
	defaults to "Ask" and is visible only at Advanced level.

	* libnautilus-extensions/nautilus-file-private.h:
	* libnautilus-extensions/nautilus-file.h: Moved
	nautilus_file_contains_text into public header.

	* src/file-manager/fm-directory-view.c:
	(get_executable_text_file_action): New function, uses preference
	and dialog (if necessary) to determine how to handle activating
	an executable text file.
	(activate_callback): Now handles executable text files specially
	by using get_executable_text_file_action. Restructured the control
	flow a little.

	* components/music/nautilus-music-view.c: (set_album_cover),
	(play_current_file), (nautilus_music_view_update):
	* components/rpmview/nautilus-rpm-view-install.c:
	(nautilus_rpm_view_install_done):
	* components/services/summary/nautilus-view/nautilus-summary-dialogs.c:
	(nautilus_summary_login_failure_dialog),
	(generate_error_dialog):
	* components/text/nautilus-text-view.c: (file_read_callback):
	* libnautilus-extensions/nautilus-file-operations.c:
	(confirm_empty_trash),
	(handle_transfer_vfs_error), (handle_transfer_overwrite),
	(nautilus_file_operations_copy_move),
	(handle_new_folder_vfs_error),
	(nautilus_file_operations_move_to_trash):
	* libnautilus-extensions/nautilus-icon-dnd.c:
	(confirm_switch_to_manual_layout):
	* libnautilus-extensions/nautilus-program-chooser.c:
	(nautilus_program_chooser_show_no_choices_message):
	* libnautilus-extensions/nautilus-program-choosing.c:
	(nautilus_launch_application):
	* libnautilus-extensions/nautilus-volume-monitor.c:
	(display_mount_status):
	* src/file-manager/fm-desktop-icon-view.c:
	(icon_view_create_nautilus_links):
	* src/file-manager/fm-directory-view.c:
	(fm_directory_view_confirm_multiple_windows),
	(real_file_limit_reached), (fm_directory_view_confirm_deletion),
	(confirm_delete_from_trash), (report_broken_symbolic_link),
	* src/file-manager/fm-error-reporting.c:
	(fm_report_error_renaming_file), (fm_report_error_setting_group),
	(fm_report_error_setting_owner),
	(fm_report_error_setting_permissions):
	* src/file-manager/fm-properties-window.c: (set_custom_image):
	* src/file-manager/fm-search-list-view.c: (load_location_callback),
	(load_error_callback), (display_indexed_search_problems_dialog),
	(real_file_limit_reached):
	* src/file-manager/nautilus-indexing-info.c:
	(update_file_index_callback),
	(show_search_service_not_available_dialog):
	* src/nautilus-application.c: (check_required_directories),
	(nautilus_application_startup):
	* src/nautilus-location-bar.c: (drag_data_received_callback):
	* src/nautilus-property-browser.c: (remove_pattern),
	(remove_emblem), (emblem_image_file_changed),
	(add_pattern_to_browser), (add_color_to_browser),
	(emblem_dialog_clicked):
	* src/nautilus-sidebar.c: (receive_dropped_uri_list):
	* src/nautilus-theme-selector.c: (add_theme_to_icons),
	(theme_select_row_callback):
	* src/nautilus-window-manage-views.c: (handle_unreadable_location),
	(report_content_view_failure_to_user_internal),
	(report_sidebar_panel_failure_to_user),
	(nautilus_window_end_location_change_callback):
	* src/nautilus-window-menus.c: (forget_history_if_confirmed),
	(show_bogus_bookmark_window): Updated for dialog API name changes.

	* libnautilus-extensions/nautilus-file.c: (get_description):
	Lucky Aaron gets missing mime description complaints now.