Bumped version to 0.6 in Rakefile.
Removed obsolete demos.
GameObject specs uses HasTransform / Drawable specs.
Updated Shape specs.
Cleaned HasTransform specs a bit.
Made HasTransform spec to a shared spec.
Renamed hastransform_spec -> shared_hastransform_spec.
Shape spec uses shared drawable spec.
GameObject uses Drawable.
Shape class uses Drawable.
Refactored code to make Rebirth::Drawable mixin.
Moved real drawing code to GameObject#_draw.
Added GL transformation stuff for GameObject.
GameObject#initialize taken options, calls super.
Cleaned up indentation in camera.rb.
No more GL depth test in Camera.
Box doesn't draw with z = @depth anymore.
GameObject#draw mixes and sorts children and shapes.
Fix GameObject draw specs.
Ordered stubs only work within one object. D'oh.
GameObject should draw shapes and children intermixed.
GameObject#draw draws shapes in order.
GameObject should draw its shapes in descending depth order.
GameObject#draw draws children in order by descending depth.
GameObject should draw its children in descending depth order.
Added empty GameObject#draw.
GameObject should be able to draw.
GameObject includes HasEventHandler.
GameObject should include HasEventHandler.
GameObject#add_shapes ignores duplicates.
GameObject should not add shapes it already has.
GameObject#add_children ignores duplicates.
GameObject should not add children it already has.
GameObject removing a missing shape should have no effect.