AirSwipe Crash Prevention

Added a protective measure to check the amount of entities that are
about to have their velocities changed before moving them all. If there
are too many entities around it will damage them without changing their
velocity, that way we don't lag out and crash due to the firing of too
many EntityCollisionEvents.
Merge remote-tracking branch 'upstream/master'
LavaFlow not cleaning while shift held.

Fixed a bug where LavaFlow was not being removed if the user kept the
shift button held down. Now it cleans up regardless of whether they are
still trying to bend a LavaFlow.
WaterWave now works with Passive, and doesn't create currents

WaterWave previously was not working with WaterPassive, now it does.
WaterWave was also removing the block of water that the user was using
as a source, which was causing currents to form in the water.
Merge pull request #34 from nathank33/master

LavaFlow issue and WaterWave Improvements