- Bug fix - use .Errorf() instead of .Error():
Before this change, an error message for failed tests in files/set_test.go
wrongly tried to use format strings in a call to .Error()
- Change event constants to be of type EventType rather than untyped integers.
- Slightly relax the locking for registry cache lookups:
For read access to Discover.registry we only need to take a read lock.
- Some cosmetic fixes.
