Update gtk_signals.defs with Gesture and LockButton

* gtk/src/gtk_signals.defs: Update.
* tools/extra_defs_gen/generate_defs_gtk.cc: Generate info for EventController
Gesture* and LockButton.
Add Gtk::EventController and Gtk::Gesture* classes.

* gtk/src/eventcontroller.[hg|ccg]:
* gtk/src/gesture.[hg|ccg]:
* gtk/src/gesturedrag.[hg|ccg]:
* gtk/src/gesturelongpress.[hg|ccg]:
* gtk/src/gesturemultipress.[hg|ccg]:
* gtk/src/gesturepan.[hg|ccg]:
* gtk/src/gesturerotate.[hg|ccg]:
* gtk/src/gesturesingle.[hg|ccg]:
* gtk/src/gestureswipe.[hg|ccg]:
* gtk/src/gesturezoom.[hg|ccg]: New files.
* gtk/src/filelist.am:
* gtk/gtkmm.h: Add new files.
* tools/m4/convert_gtk.m4: Add conversions for new enums.
* .gitignore: Add new files in gtk/gtkmm.