Added rm_digest_read_binary to allow getting in-progress digest values
added pseudo-512bit digest options city512 and murmur512
(these are just 4 x 128-bit digests with different seeds)
removed foolish rand() stuff
Use passed seed value for CITY, MURMUR, CITY512 and MURMUR512
Merge upstream changes from branch 'sahib/develop'

Conflicts:
	src/checksum.c (accepted sahib version)
	src/checksum.h (accepted sahib version)
Added CITY256 and MURMUR256
Merge pull request #61 from SeeSpotRun/city256

City256