Designer productivity improvements

First of all thanks for the good work, keep it up :)

I wrote my first bigger workflow using designer and here are my opinions now that I've really tried to use it.
I think following points should have high priority if anyone wants to use designer in a serious project.

1. Documentation for each activity output(s) is sorely missing (have to go to code to find out what it offers, or JSON.stringify it, if that works, sometimes it does not :() - elsa-workflows/elsa-gitbook#88
2. Undo/redo - elsa-workflows/elsa-core#794 - I hated this one, had to export and import a lot to be able to go back if I did something wrong
3. Copy/paste - elsa-workflows/elsa-core#792
4. Double click to open - used to work with elsa-workflows/elsa-core#790 but it stopped now in elsa-workflows/elsa-core#1114
5. Cancel keyboard to cancel activity dialog and enter (or ctrl+ enter) to apply/save - would save me a lot of scrolling - elsa-workflows/elsa-core#1114
6. Select and copy/paste or delete multiple - elsa-workflows/elsa-core#791
7. Error outputs on activities, not just done or workflow fault - designer application writer must be able to handle (at least some of the errors) that happen during workflow execution, this is a must. One obvious example would be network glitch when using http request, I want to be able to know and try to retry if I wish so from within designer. Currently it would just fault the workflow. This one is actually a showstopper because you cannot workaround it in any way..... - elsa-workflows/elsa-core#1115
8. Standard scrolling and zooming in designer - elsa-workflows/elsa-core#1139

Having 7 of those implemented would tremendously improve developer experience with designer.

If you want I can submit 1, 4, 5 and 7 as separate request but I kind of fear that there are too many issues open already so I would just swamp with them and they would be forgotten once they are on page 10 of issues :).

Thanks.