v4l2 - update handler, source resolution change, control of secondary instance creation
stream - silence calls hangups by timeout
ua - hangup_other_calls fixed for work with multiple accounts

	modified:   include/baresip.h
	modified:   modules/v4l2/v4l2.c
	modified:   src/config.c
	modified:   src/core.h
	modified:   src/stream.c
	modified:   src/ua.c