MP improvements and fixes:
+ Chunks should now only go to the player that requested them, reducing lag and lockups
+ Reduced data sent over the sockets by filtering out some useless information.
+ Projectiles are less likely to crash the game now.
+ Converted a large percent of the block types to a constant value. The constants equal the same as the previous values (1 - pick; 2 - axe) for backwards compatability.
+ More safeties and network optimizations.