Replace bitcoin POW with a brand-new Casino Consensus Protocol

 A consensus protocol for fairness.  The prototype is on https://github.com/ytop/ybtc

*If you are interested at this project, join it.

Casino Consensus Protocol
====================
Miner from lucky guy.

Genesis Contract
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The Genesis Contract is created when chain kicks off. This super contract annoucnes the rule for mining:

1. Miner chosen from contract only
2. Cadidate miner has tokens
3. Minus 1 token for each candidate miner every phase
4. Winners are randomly selected by uniform distruibution
5. The random seed in #4 is hash value from streamed winners' addresses in last phase

Phase and Winner
---------------------

Each phase has (P) blocks. There are (N) winners in one phase. P can be diveded by N.

N winners mine blocks with assigned sequence.

These dependencies are required:

Net                | P                       | N

Testnet        | 8                        | 2
Mainnet      | 16                      | 16

Exception Handling
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The previous successful miners can pick up orphan block if assigned miner is absent. The more
recently successful miner, the more possibility to be orphan picker.

Reward
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The miner has 4 rewards:

1. Coin base reward, 8 Ycoin each block in 4 years. After that, each year 3% of total delivered Ycoin.
2. Transaction fee
3. Contract gas fee
4. Casino token of last phase