Added Rectangle.pad()

Signed-off-by: Grant Skinner <info@gskinner.com>
Improved handling of filter offsets to prevent jittering.

Signed-off-by: Grant Skinner <info@gskinner.com>
Improved BlurFilter results & Filter.getBounds handling.

Signed-off-by: Grant Skinner <info@gskinner.com>
Added Bitmap performance test.

Signed-off-by: Grant Skinner <info@gskinner.com>