```Go
e := log.EventBegin(ctx, "provide")
e.Done()

e := log.EventBegin(ctx, "provide")
e.Close() // implements io.Closer in case you want to register with some lifecycle management system.
```

more d3 niceness.

race fixes

All the datastores used by pinners and so on should be mutex
wrapped. One issue with changing all of them from
ds.Datastore -> ds.ThreadSafeDatastore is that we wrap the
incoming ds.ThreadSafeDatastore with other datastores, which
do not implement the interface. Re-wrapping again causes
double locking. (which may be ok..., but...) any ideas?

testutil ci pkgs check env vars

Good thing, i checked one wrong, too!

diag/net: visualizing in d3 and dot

refactor(fsrepo.FSRepo): manage the Datastore and daemon.lock

"for each desired change, make the change easy (warning: this may be
hard), then make the easy change" - Kent Beck

https://twitter.com/KentBeck/status/250733358307500032

http://martinfowler.com/articles/preparatory-refactoring-example.html

cc @jbenet @whyrusleeping

The struct was getting unmanageable. extracted the config component to
reduce complexity. The datastore will be written as another component.

fix(fsrepo): extract private, unsynced method to prevent deadlock

no issue detected but it's good to be safe

NB: daemon is one spot the repo lock is typically acquired