PTB BETA RELEASE "Hammertime!"

* PTB for 32-Bit Matlab on Windows now uses and requires the GStreamer SDK instead of OSSBuilds GStreamer.
* Bugfix for GStreamer on Windows for special pixelformat >= 6.
* Bugfix for Linux + PsychHID.
* Bugfix for OSX crash at window close due to Apple CVDisplayLink bugs on Matlab R2013b.
* OpenGL context sharing support between windowed and fullscreen windows on OSX.
* Improved GUI window support.
* Low-level support for latest AMD GPU's on Linux and with OSX PsychtoolboxKernelDriver.
* WinTabMex support now also for 64-Bit Matlab on Windows.
* And in PlayMoviesDemo's cool section: "Stop! Hammertime!"