move bit and nybble handling to unsigned
move bit and nybble handling to unsigned

bits are unsigned by definition (otherwise they'd just be signed nothingness)
nybbles are hard to do signed (hardware and compiler support are uncommon) and not really all that useful.

youprofit/parrot,FROGGS/parrot,tkob/parrot,gagern/parrot,youprofit/parrot,parrot/parrot,tkob/parrot,youprofit/parrot,gagern/parrot,parrot/parrot,tkob/parrot,tkob/parrot,youprofit/parrot,FROGGS/parrot,FROGGS/parrot,parrot/parrot,FROGGS/parrot,gitster/parrot,tkob/parrot,gitster/parrot,gitster/parrot,youprofit/parrot,youprofit/parrot,FROGGS/parrot,gagern/parrot,gitster/parrot,FROGGS/parrot,FROGGS/parrot,gagern/parrot,tkob/parrot,FROGGS/parrot,gagern/parrot,youprofit/parrot,gitster/parrot,gagern/parrot,gitster/parrot,parrot/parrot,youprofit/parrot,parrot/parrot,tkob/parrot,tkob/parrot,gagern/parrot,gitster/parrot