Stereoscopic configuration issues

I was trying to transition a piece of software that supports stereo 3d from 1.5.2 to 1.6, but found it wouldn't actually detect whether or not stereo is supported or not. The "best configuration" generated based on the specifications turned out to be the issue.

On systems which have support for stereoscopic 3D (most quadros, etc), even if the driver has specified that it is on, using getBestConfiguration does not yield a configuration that ever says that stereo is supported unless if it is created as stereo REQUIRED, which defeats the purpose of PREFERRED, because if it's REQUIRED and not actually available, it is expected to return null according to the documentation, which it doesn't seem to do either.

I fixed this issue by finding the commit that broke this, and it had to do with a graphics configuration change for mac (which was merged into your trunk from another fork). Most of the code in these commits were based on how the prior commit functioned. I thought you might want to integrate at least some of these changes.

*Note:*
1. The last commit involving the eye swapping is something that is specific to the systems that I'm using because there is no support to swap eyes in a hardware configuration.
2. I have only tested these changes on Windows.