A batch of miscellaneous bug fixes

Another big pull request (289 additions + 103 deletions) but they are all _bug fixes_. If it's still too big for even that then I'll open a pull request for the refactor branch.

Changes:

* Fixed some chat commands returning silently.
* Fixed /buyhealth being broken.
* Fixed a Lua error in /togglegroupownable.
* Fixed a Lua error that occurs when you use too little arguments in the rp_mayor_setsalary concommand.
* Fixed an issue where the 'Set MOTD' Derma menu containing hard-to-read text.
* Fixed /removeowner printing two error notifications if the door is not ownable.
* Fixed duplicate log messages when force-giving and force-removing gun licenses.
* Fixed #609 for wanted, unwanted and warrant scoreboard buttons.
* Fixed #609 for door titles.
* Removed left-over references to the now removed help section of the scoreboard.