Introduce Basic Heartbeat mechanics

Adding a heartbeat to a block, removing a heartbeat from a block,
creating a new heartbeat.

Most of the functions are just filler, comments explaining what should
happen.
refined entropy tests
Change block to having a map of heartbeats

Also added a bunch of skeleton functions to be filled out soon.
Small change to reflect a change in function name
Added 'state.go' to manage the state

Right now it is just a struct.

DRNGSeed holds the current random number seed for the state.
SecretEntropy holds EntropyStage2 for the next heartbeat
SecretFileProof holds FileProofStage2 for the next heartbeat

ActiveBlock is the block currently being built by the concensus
algorithms. It is being updated as heartbeats come in and will be
refreshed when a block is announced and committed within the blockchain.