MacGui: Fix the quality slider setting when using presets for ffmpeg and theora.

MacGui: Fix the quality slider setting when using presets for ffmpeg and theora.
- Fix issue where ffmpeg's presets were 2.0 low on the slider.
- Fix theora presets to recognize that the slider is not "inverted" (qp value go higher as quality increases).
-Tested all tree encoders to verify that value saved in preset is reset in gui and reported correctly by libhb.

git-svn-id: svn://localhost/HandBrake/trunk@2614 b64f7644-9d1e-0410-96f1-a4d463321fa5