Initial import of DiscoveryCommunity
Some fixes
Fix similarity request conversion
Limit number of preferences/taste buddies in a message
Fix for pending_tasks
Fixes
Tracker fix
Call _resolve_bootstrap_candidates after initialize
Move associate stuff from WalkCandidate to Candidate
Less debugging
Add assert
Should use request_cache.pop
Make loading the DiscoveryCommunity optional
Fix
Fix overlap count
Fix ATB sorting + introduce_me_to
Make sure ATBs are WalkCandidates
Should not send a peer its own overlap
Fix introduce_me_to
More debug