Merge pull request #1101 from fr500/master

fix issue 1097
stop using thr->frame.within_thread for thread_set_osd_msg.
TODO: find a more reliable way to determine if the calling thread is the
video driver thread or not.
Merge pull request #1102 from aliaspider/master

stop using thr->frame.within_thread for thread_set_osd_msg.
(Menu) Remove menu->last_time - unused
Avoid usage of term 'emulator'
Add support for more Network Commands.
Merge pull request #1103 from a-shark/master

Add support for more Network Commands.
Create RARCH_CMD_AUDIO_MUTE_TOGGLE
Create RARCH_CMD_PAUSE_TOGGLE
Add RARCH_CMD_GRAB_MOUSE_TOGGLE
Add RARCH_CMD_NETPLAY_FLIP_PLAYERS and RARCH_CMD_FULLSCREEN_TOGGLE
Add has_windowed to video driver and graphics context driver
If video driver/video context driver doesn't support windowed mode,
then treat RARCH_CMD_FULLSCREEN_TOGGLE as no-op
With need_fullpath == True and a zipped game image, RA did not clean up properly afterwards. Now the image is deleted again after exit.
Create unique names for context driver static functions - needed
for Griffin builds
Uniquely name each static function for GLX context driver
More name uniformity in font renderer implementation functions
Provide explanation for not performing RARCH_CMD_FULLSCREEN_TOGGLE
Add RARCH_CMD_OVERLAY_NEXT
Put some safety checks in core_options.c functions