Bug 708174 - A text based intent driving tool for GIMP (Tito)
Bug 708174 - Improve the original search dialog patch.

Fix various bugs, improve code design and efficiency, change feature
name, update the feature up to our standards (now uses GIMP preferences,
session management, less overwhelming settings...).
Also now action history is tightly tied to GimpAction and logs all
action activation (however it activates, and the show_unavailable
parameter also applies to history).
Search algorithm greatly improved with basic tokenization, better
ordering, filtering, etc.
Add new action search dialog to POTFILES.in

Fix failing 'make check' by adding app/dialogs/action-search-dialog.c
to /po/POTFILES.in.
app: clean up the new action search a bit

- order some stuff alphabetically and consistently
- move action from help-actions to dialogs-actions
- fix OS/X menu item fiddling (untested)
app: more action search cleanup

- standard copyright headers
- use gtk_action_is_sensitive() not get_sensitive()
- formatting