Track modified size in TxMemPoolEntry so that we can correctly compute priority.
Create new BlockPolicyEstimator and use it as a replacement for the fee estiamtes from MinerPolicyEstimator
handle edge case
Bug fix for calcBlocksToConfirm
Various cleanups
Add priority estimation and code clean up

Conflicts:
	src/txmempool.h
Add read/write to fee_estimates.dat.
In the process convert arrays to vectors.

Conflicts:
	src/txmempool.cpp
	src/txmempool.h
minor touchups
fix bug in calculation of cumulative percentage
minor printing diffs