TODO

* implement proper size computation for name cache

* upgrade to new version at fixed height:
  - P2SH as enforced soft fork (BIP16)
  - strict BIP30 as enforced soft fork
  - allow larger blocks (DB locks)
  - no need to disallow auxpow parent blocks with auxpow-flag in the version
    any more; instead, the auxpow is simply never loaded for them
  - disallow legacy blocks also on testnet
  - restrict auxpow size / coinbase tx size?
  - name_new format change?
  - make NamecoinTxVersion a flag / irrelevant
  - more differences???

* reenable some of the disabled tests, new alert keys?

* make dust spam unspendable?

* dropexpirednames=1 to also remove expired names from the name database?

* simplify regtests with reduced number of nodes?