comment out assert which can sometimes trigger.
oops! add missing check. corresponding Satoshi code:

    // Hash type is one byte tacked on to the end of the signature
    if (vchSig.empty())
        return false;
    if (nHashType == 0)
        nHashType = vchSig.back();
    else if (nHashType != vchSig.back())
        return false;
    vchSig.pop_back();

libbitcoin tries not to use function selector parameters, but we still need to check the signature.
[doc] Describe optional configure flags in README
updated doc examples.
updated doc examples.
improved deserializer's read_variable_uint()
correct mistaken legacy sigops count thanks to peter todd.
Fixes issue when generating pub key.

https://github.com/spesmilo/sx/issues/12

If the pub key y or x value starts with 00, it is ignored, leaving with a 31 byte value instead of 32