d3view is now in its own repo:
https://github.com/jbenet/ipfs-diag-net-d3-vis

This is so we can iterate on it quickly without having to
needlessly waste CI resources.

The repo also installs it for you:

```sh
git clone github.com/jbenet/ipfs-diag-net-d3-vis d3view
cd d3view
sudo make install
```

Feat/eventbegin

fix: privatize Mux fields

hotfix(FSRepo) allow multiple goroutines to call 

doh! I forgot to make sure leveldb is only opened once. thanks for catching this @mappum

* You may be wondering why we don't just share pointers to FSRepos. We
  want to manage the lifecycle of the FSRepo by tracking its `state`.
  Thus each FSRepo/goroutine requires private instance variables. For
  this reason, each `fsrepo.At(p)` caller must get its own goroutine.

* There's a test in `fsrepo` because callers desire the ability to Open
  from multiple goroutines. There's a test in `component` because this
  is where the actual work needs to go in order to provide the desired
  contract. If the `component` package moves, the assurances need to
  move along with it.

cc @whyrusleeping @jbenet

side note: there are a couple packages in FSRepo that it might be
worthwhile to extract once the dust settles on this feature-set.

@jbenet will move in upcoming branch/PR

feat(eventlog): e := EventBegin; e.Done()

```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