Todd's initial circle collision code.
Fixed circle/rectangle collision movement bug that occurs when corner of a rectangle moves into the arc of a circle.
Restructured collision-group to use component factory.
Put in a check to prevent collision resolution from moving entities in the opposite direction from the collision check due to floating point inaccuracies.
Enabled jump-through collision for right, left, and bottom in addition to the top collision already in place.
Todd's improvements to tiled-loader to allow loading of Tiled map grids.
Fixed collision-group and collision-basic to allow multiple shapes per entity.
Added better support for multiple collision-basic components on a single entity.
Implemented stepping to ensure fast moving entities do not go through other objects.
Implemented "bullet" property so collision-basic can be either more thorough or faster.
Fixed bug with colliding entities sometimes sticking together.
Fixed falling bug due to prevAABB being used incorrectly.
Updated Group Collision to render in render-debug.
Basic non-interference carrying re-implemented.
Created group helper functions in preparation for sub-group collision fixes.
Entities can now be carried, but noting odd collision issues with rising platforms.
Fixed logic-gravity and logic-jump components so that default values for Y acceleration would not override a setting of 0 from the component definition.
Fixed vertical collision bug with moving platforms.
Merge branch 'circle-collision' of https://github.com/gopherwood/Platypus into gw-pond
Todd's updated vector class.