MusterCull - Minor tweaks to priority and refactoring, status and new command.
- Updated priority for muster cull to remove leashed mobs from priority list.
- Refactored a bit around "getting living non-player mobs" to remove duplication.
- Added hard culling information to /mcullstatus.  This includes runtime, average
runtime, number of times a cull has happened, and how many times a penalty
purge is part of said cull.
- Added command to change purge strategy - /mcullhardlimitstrategy - which takes
either PRIORITY or RANDOM.  This will switch the culling strategy appropriately.
- Forced the ticks between hard cap damage to ignore any value set less than 200.
- Updated documentation.