Remove old Stake Modifier Checkpoints

kernel.cpp
Use BlackCoin PoS 2.0 Protocol Weight Calculation

- Default to CheckStakeKernelHashV2
- Comment out CheckStakeKernelHashV1 but keep for reference.
Delay full PoS 2.0 Switch to 1 year

2.0 Weight calculation still from day 1.
Adjust Split/Combine cutoffs

- 5 Day maximum to split
- 100,000 coin minimum for combine
Stylesheet Edits