RegisterHotKey implementation

[Robert Reif]

Here is a partial RegisterHotKey and UnRegisterHotKey
patch which works for the keys I need but is incomplete
for modifier keys.  You must run tools/make_X11wrappers
before compiling or you will get errors.  I don't  have the time
for a few weeks to finish it or look into what is needed to
make it complete.  I hope someone can take this and get
it ready for including.

Thanks,

Bob.