Documentation: Entity + small helper change

Lots of documentation added to Entity, and a small change was made to
get rid of unnecessary references for the EntityHelper functions.
Code cleanup; removed dead code
Clean up; removing dead code from Entity
Clean up; removing commented out code from AS
Added WATER tile attribute
Removed MapTestState from compliation
Starting "ladder" tracing refactor
Added ladder tracing and rendering
MSVC fixes for emplace_back

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Changed ladder bounds from int to float

This reduces the need to copy-construct or convert BoundingBox<int> to
BoundingBox<float>.
Changed ladder rendering slightly
Fixed unnecessary copying of BoundingBox

MIssing a &!
Got rid of unnecessary copying for GOs

The copy constructors were copying data twice. Moved copying up into
the Entity copy constructor so that it gets handled in the right place.
Added ceil/floor methods to Vector2
Clean up: Entity

Removed unneeded includes, cleaned up some of the code based on changes
to Vector and pass-by-reference.
Clean up: Enemy

Using methods rather than touching body directly.
Documentation: Entity

Added some documentation to Entity's interface.
Entity: made room private; use accessor

Updated Hero too since it uses the Room pointer.
Fixed shooting + jumping
Merge pull request #105 from zackthehuman/master

Lots of clean up and documentation; started new ladder detection