Automate spawning of bots

When 1 player joins an empty server, 5 bots are spawned and configured
to be
"unconfirmed".  As long as the bots stay unconfirmed (meaning sh_bots is
not called succesfully), the bots are added/removed as players come/go
according to the following algorithm (with the results rounded),
displayed at http://tinyurl.com/mcbhpna

( number of players / 2 )^2 + 5