webgl webcam test driver
doesn't work on firefox, see https://bugzilla.mozilla.org/show_bug.cgi?id=917314
[EMSCRIPTEN] webcam improvments
Merge branch 'master' of https://github.com/libretro/RetroArch into webcam-test

Conflicts:
	Makefile.emscripten
move prototype camera interface to libretro interface - GL texture only for now
Merge pull request #385 from libretro/webcam-test

Emscripten webcam driver