reworking gravity. I need to get tunneling to work with gravity. I cannot have unfilled pockets of nothing in my liquids!
also added pipe material
trying to get gravity to work with tunneling (where the material goes through itself to get somewhere else)
Release v0.3 - Added Pipes and Reworked Gravity

Pipes transport water straight up.
gravity now treats water more liquid-like. there is a new technique that i'm calling "tunneling" that i'm using. it is when a material gets to a lower place in the grid by "tunneling" through other materials of the same kind.
minor
Merge branch 'master' into gravity

Conflicts:
	cell_engine.h