build on macosx
windows build fix + new project file for the example
remove _opt suffix from vr_get_opt/vr_set_opt, and _OPT_from the predefined names
added vr_get_def functions
added vr_get?_def functions which allow a default to be specified
fixed call to ovrHmd_ConfigureTracking to stop setting the ovrTrackingCap_Idle bit
added VR_EYE_RES_SCALE option
renamed VR_EYE_RES_SCALE to VR_RENDER_RES_SCALE
added convenience options: VR_RENDER_XRES & VR_RENDER_YRES, which are derived
from VR_LEYE_XRES, VR_REYE_XRES, etc.