HORNET-0.5.0-rc7

Breaking change:
** DO NOT USE IT ON MAINNET, IT WILL CRASH IMMEDIATELY AND IT WILL DESTROY YOUR DATABASE !!! **

Changed

- URTS now uses separate tip-pools for semi- and non-lazy to prevent below-max-depth attacks
- Coordinator now waits until the milestone is solid
- Definition of semi-lazy tips in URTS was changed
- Spammer now tries to reduce semi-lazy tips if certain threshold reached
- Use dag helper in whiteflag (#583)

Fixed

- Coordinator bootstrapping
- Peering configs now recognized via CLI
- Error reason for connection abort is now shown
- Deadlock in snapshotting and pruning
- Fix wrong approveeHashes in URTS calculateScore