Add support for both compressed and uncompressed addresses

-Added support for both compressed and uncompressed addresses. -u (uncompressed) and -c (compressed) can be specified on the commandline. Default is compressed. If both are specified, then the key finder will check both compressed and uncompressed keys.
-Bug in secp256k1.cu multiplication code would produce wrong results on in rare cases.
-Bug in uint256 division code would produce incorrect results