Grass now grows under up-side-down slabs
Remove old function
Merge branch 'master' into Slabs

Conflicts:
	src/Blocks/BlockDirt.h
Add CanChangeDirtToGrass function to Block Handlers.
Merge branch 'master' into Slabs
Remove old import
Small changes
Some change to Entity.cpp

* Added comments to BroadcastMovementUpdate() and the collision tracer
Merge branch 'master' into fixes

Conflicts:
	src/World.h
Implemented suggestions
More comments!

* Also fixed a potential issue with position sending - if someone moved
slowly enough, their position would never be updated.
A tiny speed improvement in ApplyFoodExhaustion()
Redstone simulator now directly accesses cChunk

* Redstone simulator performance improvements
* Added return values to some functions
* Minor fixes
Merge branch 'master' into fixes.
A bit of reformatting.
Attempted fix for CLang warnings in Vector3.h.

C++11 seems to have deprecated classes that have custom copy-constructor but not a custom assignment operator.
Fixed vanilla fluid simulator.

Fixes #919.
Implemented a true assignment operator for Vector3.
Fixed float comparison warnings in Vector3.

There's a bitwise comparison (Equals), and there's Eps-based comparison (EqualsEps).
Removed the controversial Vector3::operator <.

It hasn't been used in any C++ code and Lua doesn't need it.