HostComputer exif field containing serial number was replaced with more
suitable CameraSerialNumber. IPTCNAA field containing frame number was
replaced with ImageNumber.

This field corresponds to sensor port number

circbuf_start.sh helper script was also added. It should be copied to
camera.

Fix source code formatting with 'uncrustify' command-line utility

This commit adds almost non modified files from elphel353 source tree.
Changes made to source files include additional debug output, commented
out code and updates to source paths in makefile and includes.