0) Adjust BIP30 enforcement values
1) Reduce amount that peers can adjust our time to eliminate an attack vector. Thanks to
coblee for this fix.
2) Zeitgeist2 patch - thanks to Lolcust and ArtForz. This fixes an issue where a
51% attack can change difficulty at will. Go back the full period unless it's the
first retarget after genesis.
3) Avoid overflow in CalculateNextWorkRequired(). Thanks to pooler for the overflow fix.
4) Zeitgeist2 bool fshift bnNew.bits(). Thanks to romanornr for this path.
5) SegWit ContextualCheckBlockHeader adjustment and extra coverage.
6) Reject peer proto version below 70002. Thanks to wtogami for this patch.
7) Send final alert message to nodes warning about removal of the alert system. Thanks to coblee for this patch.
8) Adjust default settings for Litecoin.
