bug#16109: 24.3.50; <kp-delete> doesn't delete region in delete-selection-mode

[Juri Linkov <juri@jurta.org>]

In delete-selection-mode, <delete> deletes the region, but
its keypad counterpart <kp-delete> doesn't delete the region.

This is what `C-h k <delete>' displays:

    <deletechar> (translated from <delete>) runs the command
    delete-forward-char, which is an interactive compiled Lisp function in
    `simple.el'.

And this is displayed by `C-h k <kp-delete>':

    C-d (translated from <kp-delete>) runs the command
    delete-char, which is an interactive built-in function in
    `cmds.c'.

What could be done:

1. Change `delete-char' to delete the active region (might need a poll
since I recall some disagreements about this default).

2. Bind <kp-delete> to the same command `delete-forward-char'
as for <delete>.

3. Add `delete-char' back to delsel.el since typing `C-d' is handy
anyway to delete the region.