Added truncation of leading zeros, and fixed the case where we would multiply using a bigint set to 0, which would result in many words set to 0.
Implemented division by multi-precision integers. Still requires testing.
Removed a temporarily allocated mp int that I had missed earlier. Instead uint methods are now used.
Reinstated division and modulus calculations in the python test script.
Fixed a typo that would attempt to allocate a zero-length vector, which is not allowed.