[Vimprobable-users] Move commands to main.c, get rid of COMMANDSIZE

[Morgan H. <mt...@gm...>]

This patch moves the commands out of the header file and into main.c
and makes the COMMANDSIZE a compile time calculated const value. This
makes it so we don't need to remember to update that value each time a
new command is added, reduces likelihood of merge conflicts when
adding new commands, and should make things a bit more flexible in the
future (user defined colon commands?).

Regards,
Morgan