New plugin: Blue Banana color grading/correction filter

Blue Banana offers slider-based range and non-linear (gamma)
adjustment for red, green, blue, hue, saturation and value.  It
provides feedback both through the compositor window and realtime
color histograms embedded in each adjustment slider. It can operate
on the entire frame, select specific subset of colors, the current
masked region, or a combination of a selection and a mask. It is also
able to highlight the selected region with a marching zebra.

Commit 5129a9c43dfc6fa762527e749e6756fb7e48ad23 from
http://git.xiph.org/?p=users/xiphmont/bluebanana.git;a=summary
Release fonts on closing main window

Plug the leak by freeing the fonts in the destructor when destroying the main window.
Then the font structure is freed during closing the last window.

The change is discovered and tested in valgrind.
Avoid casting away const qualifier in byteorder detection code

Killed warning: "cast from type 'const char*’ to type 'u_int32_t*'"
The code return 1 if little endian and 0 if big or middle endian.
Include <stdlib.h> to find free() in libmpeg3 code

Killed warning: "incompatible implicit declaration of built-in function 'free'".
Merge branch 'master' into byteorder-const-cast