* [NOD-164] Added validation routine
* [NOD-167] Extracted acceptedIDMerkleRoot calculation to its own method and implemented NextAcceptedIDMerkleRoot.
* [NOD-164] Fixed TestValidateFeeTransaction.
* [NOD-164] Fixed TestFinality.
* [NOD-164] Fixed blk_ tests.
* [NOD-164] Fixed if -> iff in a comment.
* [NOD-164] Minor style changes in comments.
* [NOD-164] Moved validateAcceptedIDMerkleRoot to before its population with the block's own transactions.
Replaced heavy call to verifyAndBuildUTXO in NextBlockFeeTransaction and NextAcceptedIDMerkleRoot with a call to pastUTXO on the virtual.
* [NOD-164] Fixed erroneous comment.
* [NOD-164] Inserted the logic from buildAndSortAcceptedTxs into calculateAcceptedIDMerkleRoot, since the former was meaningless on its own.
* [NOD-164] Changed looping over txsAcceptanceData instead of over node.blues.
