Request global headers from ffmpeg aac encoder

FAAC and FDK AAC don't populate AVCodecContext::extradata{_size} unless
CODEC_FLAG_GLOBAL_HEADER is set
Update OSX dependencies for cmake generators other than ninja/make
Use bzalloc instead of bmalloc + memset
Use the Xinerama extension to get screen sizes
Added properties to plugin.

The capture of the mouse cursor is now configurable with the properties system.
Support multi screen setups

This adds support for setups with multiple screen by adding
an option to select the screen that should be captured.
Add offset to xcursor

This patch adds the option to specify an offset for the cursor position.