[GSdx] OpenGL PP Updates

Updates the post-processing, so that all effects now compile and output as intended for both OGL & D3D.
Also just added the OpenGL shader ini params to GSdx.ini when the user enables post-processing in the options dialog.

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Btw: when trying to commit, I had to edit the files with the bloody GitHub file editor. For some reason, I can't push/pull/commit, etc. to my pcsx2 repository, since the latest merge. I tried to delete it and re-fork. Didn't work. My other repositories work fine.