together with blockFinished() as 'commit' this introduces the ability
to modify the in-memory utxo which can be rolled-back with ease.
This allows us to "modify" the utxo while validating a block in an
optimistic manner and only spend extra resources doing a rollback
should the block end up not being Ok.
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.
This cleans up the code for sigops.
It now uses uint32_t everywhere.
It uses an atomic while counting in different threads.
I make sure that both legacy as well as p2sh sigops are counted.
The old was based on levelDB which has scalability issues and stability
issues. (most often cited problem is corrupted database..)
This unspent output database I wrote is based on the idea that we need
never actually update any rows, which makes most old fashioned databases
a bad fit.
All we do is create rows and we forget rows. So lets design a DB to fit
that pattern.
Remove no longer useful options;
* chain (sorry, supporting the btc chain just doesn't seem worth it)
* initiatecashconnections, we only allow Cash connections now.
* flexiblehandshake, same for incoming. Reject non-cash ones.
DesWurstes