Prepend existing stats for file stats store to prevent overwriting.

"validate_run" must now be called to do validation from run name. The Run must be preloaded and passed to call "validate" directly.

…to validate_patch

…acapo into validate_patch

There appear to be some python formatting errors in
f604f40. This pull request
uses the [psf/black](https://github.com/psf/black) formatter to fix
these issues.

…to validate_patch

There appear to be some python formatting errors in
cb300f5. This pull request
uses the [psf/black](https://github.com/psf/black) formatter to fix
these issues.

There appear to be some python formatting errors in
81ec675. This pull request
uses the [psf/black](https://github.com/psf/black) formatter to fix
these issues.

There appear to be some python formatting errors in
50d9833. This pull request
uses the [psf/black](https://github.com/psf/black) formatter to fix
these issues.

…to validate_patch

Fixed a couple small typos I encountered running examples

… arrays.

Also set GT to automatically be a segmentation layer in neuroglancer, for run.visualize_pipeline

There appear to be some python formatting errors in
38a1b7e. This pull request
uses the [psf/black](https://github.com/psf/black) formatter to fix
these issues.

Sometimes i want to speedup validation so as option we can limit
validation size:
`max_validation_volume_size = 600**3`

There appear to be some python formatting errors in
4583723. This pull request
uses the [psf/black](https://github.com/psf/black) formatter to fix
these issues.

…iations

There appear to be some python formatting errors in
d899c63. This pull request
uses the [psf/black](https://github.com/psf/black) formatter to fix
these issues.

This PR just adds a `bind_address` and `bind_port` parameter to all
neuroglancer instantiation calls. The parameter defaults do not change
prior behavior, and specifying bind parameters is useful for me to
access neuroglancer via ssh tunnels to a cluster that does not normally
expose any ports/addresses.

There appear to be some python formatting errors in
7794118. This pull request
uses the [psf/black](https://github.com/psf/black) formatter to fix
these issues.

There appear to be some python formatting errors in
525f2fe. This pull request
uses the [psf/black](https://github.com/psf/black) formatter to fix
these issues.

… in nan loss

Adds a simple tutorial start-to-finish tutorial for DaCapo.
Still a few things left to resolve before its ready for merging:

- [ ] Loss behaving strangely after the first validation (temporary
solution involves giving an extra singleton dimension to the provided
data)
- [ ] Validation fails (we want to show validation loss/scores,
validation outputs across iterations, and how to finally take the best
iteration and apply it with the post processing to a volume manually)
- [ ] stdout too verbose
- [ ] plotting functions should be built into `DaCapo` (there are
plotting functions, not sure how to include bokeh plots so I didn't dive
too deep into this)