Added get and set for extra PVAPI property: CV_CAP_PROP_FRAMESTARTTRIGGERMODE
Added PVAPI enums to highgui.hpp
Added "PVAPI_" prefix to FrameStartTriggerMode definition
Added missing comma in enum.
Update py_image_display.rst
Update py_image_display.rst

OS information removed.
Update py_image_display.rst
Merge pull request #2291 from xgvargas:extra-note-for-waitKey
Merge pull request #2144 from nickdademo:pvapi_framestarttriggermode
some fixes in perf tests