feat(datasource/graphene) added timestamp tool to graphene, timestamp property to SegmentationUserLayer

[chrisj]

replaces #587

This is also designed to support our future cave annotation layers being able to synchronize/control with the segmentation timestamp.

Here is part of that implementation seung-lab@4d41b32

[chrisj]

Also, can you explain what you use to organize imports? Is it using the eslintrc.yml file? The default vs code sorter wants to sort lowercase above all uppercase imports and doesn't have the same behavior with package and css imports.

[jbms]

You can use npm run format:fix and npm run lint:fix --- it is indeed eslint.

[jbms]

Can you explain the logic of timestampOwner? It looks like the purpose is to link the timestamp across layers, but why canSetTimestamp?

[chrisj]

I'm currently using timestamp owner to do a self-lock when our graphene layer has an active edit tool (owner = self + no timestamp). canSetTimestamp says you to change the timestamp when there is no owners or the only owner is the one checking. Alternatively, I could make a setter function for timestamp that does the check and also sets owner.

The cave annotation datasource has more use of timestamp owner. I plan to put up a PR for if this PR is approved.
seung-lab@5dd2b7d

The cave annotation layers have a timestamp associated with it, when it gets linked to a segmentation layer, it sets the segmentation layer to the same timestamp if possible. Multiple annotation layers with the same timestamp can be linked to the same segmentation layer. Each one gets added as an owner. Only once all of them are unlinked is the segmentation timestamp available to be changed (or if one remaining owner wants to change the timestamp it has ownership of).