The drawing is now completely shader based, which makes away
with all usage of the depracted matrix stack. This also allows
us to do things like simple translations and texture coordinate
translation directly instead of doing everything indirectly
through matrices.
Fixed vertex attributes ('vertexPointer()' etc) are also
replaced with user defined attribute arrays.
A difference to RMXP is that negative height values
will result in exceptions too.
Also change Bitmap constructors to not allocate Private
struct before potential exceptions.
Jonas Kulla