Turned down the blending level to make colored blocks obscure
the video less.
Not blending the entire block to give distinction to macro
block edges.
Added configuration so that macro block blending function can
be optimized.
Change to constrain line as to when dx and dy are computed.
Now draw two lines to form an arrow.
Change-Id: I986784e6abff65ea3e0d1437dfca7d06d44ede71
6fda7668e8