add --m32 like option for non 64bit targets

[Reini Urban]

for smaller devices.
e.g. --m16 (AVR) or --m32 (arm).

the current limitation are the hash functions mostly, even with hashes16.

or just provide fnv32, fnv16, crc32, crc16 hashes

[Reini Urban]

Done with the fnv32 and fnv16 hashes