entire buffer.
Introduced a _drawBuffer pointer which points either to _scaledBuffer or
_frameBuffer1. That way, we don't need to copy _frameBuffer1 every time we
draw an unscaled frame. (Probably the most common case by far.)
Adjusted the Broken Sword 1 DXA player for the second change. (It sneakily
avoids copying each frame by using _drawBuffer directly.)
svn-id: r24846
