Multicut: option to keep one team of annotations (red or blue) for next split at the same location

[szichieh]

At a messy location that requires multiple splits, it would be great that we have the option to keep the annotations in the neuron of interest from one split to another. So those annotations would not need to be placed over and over again.
It would be even better that one of the team could cut off multiple mergers at once. Or in a simpler way to have extra team(s)/color(s) to label more merger.

requesting on behalf of tracers

[ceesem]

Agreed, this would be nice!

On a similar vein of improving multicut location points, being able to delete points from within the multicut point list would be much more convenient than having to select them and then go to the lower right corner. This is particularly true due to misplaced points that occur due to the bug in #503 or when one uses the wrong color due to #519.

[manuel-castro]

What's required for this feature is for the ChunkedGraph to return the new root IDs that are created after a split in a specific order -- for example the "red ID" first and the "blue ID" second. The reason this is needed is because each point in the multicut tool is associated with a specific root ID, so after the ChunkedGraph splits a specific root and returns two (or more) new IDs, we need to know which ID is the "blue ID" and which is the "red ID" to reassign the multicut points. Unfortunately I didn't have time to get to this.