[tools/firmware-utils] imagetag: Significantly updated brcm63xx imagetag writing...

[tools/firmware-utils] imagetag: Significantly updated brcm63xx imagetag writing tool.
	* Rewrote commandline parsing code using gengetopt
		- We now get long options
		- We have more options including use of the info section for
			board information (e.g. to add the same boardid but
			different GPIOs on different routers)
	* Added back the ability to write stock images (this is useful, for example,
		when copying the firmware from the in-memory flash, and then being
		able to create an image that will let you revert to/test stock firmware
	* Fixed copying of CRCs to use memcpy instead of strncpy (strncpy stops at 0)
	* Added ability to use all sections of the imagetag, including custom magic
	 	signatures (e.g. for the Telsey router I'm adding soon), info sections,
		and reserved sections
	* Added putting the router type (as defined in the image generating Makefile)
		into the info1 section and the filesystem type in the info2 section.
		This will be used by mtd (when I add the code) to return the name of
		image used to flash this router.  (As requested by Jo, as well as being
		useful for same boardid different board scenario described above).

SVN-Revision: 24011