Post-Release update "Aaron Swartz" for PTB BETA RELEASE "The fun in dysfunction"

This update is dedicated to Aaron Swartz.

Some improvements to M-Files:

* Full panelfitter high-level setup support via PsychImaging('AddTask', 'General', 'UsePanelFitter'): Selection of common scaling/fitting modes. Fully compatible with all stereo display modes, high-precision display modes and other PsychImaging tasks. Also fully compatible with RemapMouse() now.

* Cleanups to BeampositionTests by Ian A.

* Robustness improvements to GStreamer-SDK detection on 64-Bit Windows.

* Tiny fixes in moglmorpher() and LoadOBJFile().

* Minor tweaks to some demos.