* debian/control.in:
  - Add IBus (build) dependency.
* debian/rules:
  - Enable IBus.
* debian/patches/revert_new_ibus_keyboard_use.patch:
* debian/patches/10_keyboard_layout_on_unity.patch:
  - Drop patches, use input sources panel.
* debian/patches/rename_screenshot_media_keys.patch:
  - Since Ubuntu's gnome-screenshot doesn't save to the Pictures directory
    automatically, don't say that it does in Keyboard>Shortcuts
* debian/patches/input-sources-text-entry.patch:
  - Implement text entry panel by modifying input sources panel.