Added -g, --oldmouse option to support of NORMAL/BUTTON_EVENT mouse type.

Added -g, --oldmouse option to support of NORMAL/BUTTON_EVENT mouse type.

Required for some terminals (screen/tmux) to force needed mouse type
(BUTTON_EVENT by default).

Normal tracking mode sends an escape sequence on both button press and release.
Mouse highlight tracking notifies a program of a button press, receives a range of
lines from the program, highlights the region covered by the mouse within that
range until button release, and then sends the program the release coordinates.
It is enabled by specifying parameter 1001 to DECSET.

Button-event tracking is essentially the same as normal tracking, but xterm also
reports button-motion events. Motion events are reported only if the mouse pointer
has moved to a different character cell. It is enabled by specifying parameter 1002 to DECSET.
On button press or release, xterm sends the same codes used by normal tracking mode.

Signed-off-by: Ilia Maslakov <il.smind@gmail.com>
changed mc.1.in, added description of command line options -g, --oldmouse.

Signed-off-by: Ilia Maslakov <il.smind@gmail.com>