The API call for GetBlock has a filter-on-address functionality which is
now ported to no longer use ripe160 addresses but instead uses output-
script hashes.
This avoids problems for transactions not using p2pkh and generally is a
cleaner solution.
This also adds a unit test to test this feature.
Also write some new accessor methods on the baseclass.
The longer term idea is to make the server itself only use the uint160
raw version for bitcoin addresses.
For now move the encodings (between that uint160 and human-readable) to
the utils library.
tomFlowee
TomZ