Reserved slots plugin

Currently only the crude password method. If UWE create proper
connection handling in Lua, I'll make a much better version.
A few fixes/improvements

- Fixed map vote plugin not always obeying the "AllowExtend" option. It
will now properly exclude the current map from all votes when set to
false.
- Added delay option back to the motd plugin. Sets how long in seconds
after a player joins (and presses a key) to display the MotD.
Merge pull request #84 from Person8880/develop

Reserved slots and fixes