Progress
Minor bugfixes
More progress. will write something more detailed when i squash this branch...
Adds utilities to deal with difficulties and targets
Fixes bug with building coinbase outputs
Fixes bug serializing prevhash into block header
Fixed mistake in bits to shares and added a test
Added optional return of the hash on verification
Added simple helper function for getting int value of a hash
Moved the ltc_scrypt extension to be installed by root setup.py