Bitmap rendering was rebuild from the original state and checked for
rendering bugs at every change. Currently the implementation supports
scaling by averagin for RGB channels an for alpha channel in some
cases. For scaling factor > 0.6, the original bilinear scaling is
used. Implementation is currently still in "outdev2" but is decoupled
and will be moved to its proper place into "bitmap" and "bitmapex".

Change-Id: I6feb744712956a92d6140d079dc3a85ee8511930