Update of RaspiStillYUV.c and burst mode

I have tried to apply the changes done to RaspiStill.c to RaspiStillYUV.c, this includes the latest addition of --settings and long exposure created by 6by9 and the different capture methods (key, signal more up to date timelapse) by JamesH65.

Additionally I have included settings and long exposure to RaspiVid.c.

Last I added the parameter -bm/--burst which activates the 'burst capture mode' to RaspiStill/RaspiStillYUV, which allow faster successive captures in still mode.