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.
The new UnspentOutputDatabase classes are only very loosly a database, we
purely register and store unspent outputs there. But unline a DB we don't
allow modification (just insert and delete).
This replaces the coin-db (which was based on leveldb) and as first goal
this gives us a higher level of stability. The level-database was known
to give corruption issues.
Notice that users will need to do a manual reindex on first update.
tomFlowee
TomZ