Release r6 of MinetickMod for Minecraft version 1.7.9

Changes from r5:

• The update time of furnaces was reduced by checking the top and fuel slot for valid input first, before attempting to start burning
• The update time of mob spawners was reduced by applying a delay after failed spawning attempts, the more fails in succession, the greater the delay
• Chunk loading favors chunks that are in front of the players
• Chunk loading does not slow down as much anymore when the server is under heavy load for a longer time
• Monsters that were set to target EntityHumans do now only target players. As checking the players list for a target is much faster, than going through the lists of the surrounding chunks
• Lowered the chances for zombies, creepers and skeletons to look for a new target (if this makes them too dull, this will be changed again)

Known issues:

• Plugins that do inter-world access from within event-handlers may cause trouble (event being called in thread of world A and modifying world B)