Review locking strategies

[StabbyCutyou]

There is possibly some naivete in how I'm locking. Possible improvements:

2 locks, one for listening, one for dialing

Move writes out of locks, break the lookup + write into 2 ops when writing to an endpoint, since conns are already threadsafe.

Synchronize access to the conn map so I need less locking code littered around map acces