Fix Lua binding of PhysicsWorld2D. Closes #250.
Exposed IsPowerOfTwo(), NextPowerOfTwo() and SDBMHash() to script.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	Source/Engine/LuaScript/pkgs/Math/MathDefs.pkg
	Source/Engine/LuaScript/pkgs/Urho2D/PhysicsWorld2D.pkg