Primecoin: Add chainsperday to model mining performance
Ported from upstream commit 86a95e596c.
Changing more references from Bitcoin to Primecoin
Primecoin: Rearrange prime.cpp by protocol section and miner section
Ported from upstream commit 1a0fb3e0cf.
Primecoin: Command 'listprimerecords' to list records inside primecoin
Primecoin: Checkpoints at block 74722, 84106, 85429
Primecoin: Show whether prime is mined by this wallet in 'listprimerecords'
           Show primorial form of prime chain origin in 'listprimerecords'