[Core][Consensus] Add Tiered Coinbase Maturation

[JSKitty]

This system is currently set to activate at block 430000 (As an example block, which can be changed later if desired). This system will enforce new rules on Coinbase rewards (Stakes) which adjusts a UTXOs maturation period based on its total output value, larger outputs of SCC will mature much faster than smaller outputs of SCC.

Previously, every reward had a maturation period of 25 blocks.

The new Coinbase/Stake maturation tiers:

• 0 - 100 scc -> 1440 blocks (about 2d)
• 100 - 500 scc -> 720 blocks (about 1d)
• 500 - 1000 scc -> 360 blocks (about 0.5d)
• 1000 scc -> 180 blocks 180 (about 0.25d)

Possible to-do's and notes:

• As this is consensus-changing, we will want to bump the protocol version and aim for a smooth upgrade.
• As this will affect how staking works, pools such as StakeCube itself will need to be adapted to recognize this tier-system, to avoid rewarding users shares for a deposit that is not yet ready for staking again (Due to not meeting the input's unique maturation period)

Code reviews and tests are heavily appreciated! - StakeCube rocks!

[stakecube]

Rebase needed;
Confirming functionality on Testnet and ack