Fix PhysicsWorld::GetRigidBodies() not taking collision layer mask into account. Closes #248.
Expose PhysicsWorld::GetRigidBodies() into Lua.
Travis CI: API documentation update at 2014-03-10 10:51:44 UTC.
[ci package]
Initial negative light support. Right now works only with per-vertex lights. Set negative light color to use. Per-pixel negative lights may be problematic, as they require different blend mode, will also darken any emissive materials, and will not work in light pre-pass mode (there is nothing to subtract from, as light buffer is initialized with black)
Handle zone search better to avoid erroneous lower-priority zone assignment. Added OnRemoveFromOctree() virtual function to Drawable. Zone code simplified. Remove zone reference from drawables within its bounding box when the zone is being destroyed.
When a Zone moves or is removed from octree, clear zone from all drawables within the bounding box, not just from those that belong to the zone. This allows zone search in View to perform more optimally.
Refactor Drawable2D's pixel-per-unit to Scene's 2D-unit-size attr.

Updating this Scene's attribute would mark all the attached Drawable2D components dirty.
Travis CI: API documentation update at 2014-03-11 08:21:59 UTC.
[ci package]
Improved zone gradient documentation.
Also recalculate bounding box when Scene's 2D unit size change.
Use proper object return type in Lua bindings of UIElement::GetChild() to enable subclass properties & functions.
Fixed the Lua binding of UIElement::GetParent() to return the proper type.
Fix MINGW_ROOT variable value computation when not being provided.
Sync at 2014-03-11 20:12:06 +0800.