This reverts commit e2a1a085b6a9f36b23128872de85da727d231882, reversing
changes made to 2aea549eef85ba165672c8355d0e90781d805efd.

Fast depth is now more accurate than slow depth and should always be used.
The option will be kept in a different form as it is still used as a hack to fix some games.
Also, the slow depth code path will still be relied upon by cards that don't support GL_ARB_clip_control.

Now we require lots of empty functions, but this removes by far more duplicated code.

This reverts commit 81414b4fa2edadf0b2a2bb0bd4df61dd59165eec, reversing
changes made to b926061f641692ae31bacbeba304f5941db7d3bc.

Conflicts:
	Source/Core/DolphinWX/Frame.cpp
	Source/Core/VideoCommon/VideoConfig.cpp
	Source/Core/VideoCommon/VideoConfig.h

MSAA: Store samples in ini files.

It was only implemented in OpenGL, though the option was visible in both
backends, leading to memory leaks if you enabled it in DirectX.

And it wasn't particularly useful as a debug feature as it only showed
where in the EFB the copies were taken from, not what format it was, or
what the copy was used for, or what content was in the EFB at that point
in time.

Also, it stretched the copy regions relative to the window, so the
on-screen regions don't even line up with the window unless the game used
the full EFB (some pal games) and you game image stretched to the full
window.

Stereo3d presets