BGE: Extend Framing Mode + Camera sensor

If the "Framing" mode is set to extend,
the camera frustrum changes when you
resizes the blenderplayer window.

Before this patch, there were no way to
control which part of the framing you want
to extend (vertical, horizontal or arbritary).

Now:
If the camera sensor fit is set to HORIZONTAL,
the horizontal field of view doesn't change.
If set to VERTICAL, the vertical fov doesn't change.

If set to AUTO the old behaviour takes place, arbitrarly
showing more of the horizontal or vertical field of view
depending on the aspect ratio of the window.

Test file:
https://svn.blender.org/svnroot/bf-blender/trunk/lib/tests/gameengine/framing_extend.blend

Bugfix supported by NF-UBC Nereus Program as part of the development
of OceanViz/NereusViz

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56155 954f8c5b-7b00-dc11-b283-0030488c597c