Fixes

fixes #649, fixes #673

To be backported:
- Allowing tinc to recover from inconsistent member states (b077c17)
- Forcing tinc even more to put endpoints near vms (037a93f)
- Treating connection creation errors on hosts as internal error (261ba85)
- Reloading information on invalid state error (fb78175)
- Clustering tinc peers to avoid n^2 connections (7dd64f4)
- Allowing active bridges to be removed (b7f8f14)
- More locking for connections (d49d624)