git-gui: Handle Ctrl + BS/Del in the commit msg
- Control+BackSpace: Delete word to the left of the cursor.
- Control+Delete : Delete word to the right of the cursor.
Originally introduced by BRIEF and Turbo Vision between 1985 and 1992,
they were adopted by most CUA-Compliant UIs, including those of: OS/2,
Windows, Mac OS, Qt, GTK, Open/Libre Office, Gecko, and GNU Emacs.
In both cases Tk already implements the functionality bound to other key
combination, so we use that.
Graphical examples:
Deleting to the left:
v------ pointer
X_WORD____X
^-----^------ selection
Deleting to the right:
v--------- pointer
X_WORD_X
^--^------ selection
Signed-off-by: Ismael Luceno <ismael.luceno@tttech-auto.com>
Signed-off-by: Pratyush Yadav <me@yadavpratyush.com>