Revert "v4l2 - update handler, source resolution change, control of secondary instance creation"

This reverts commit 9062d751aa75afa3d989da814fef1366af27f71e.

	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
Revert "Revert "v4l2 - update handler, source resolution change, control of secondary instance creation""

This reverts commit ea19345229ce3582bfc57baf547facc5c20d06ff.

	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