Sanitize group name when using with dotin import

[marcospb19]

Example:

dotin import folder/a folder/b

In this case, it is possible to detect that folder/a is not a proper group name, because it contains a slash.

Question: does this sanitization applies to other commands as well?

[marcospb19]

I should add tests to see what dotin [un]link a/b does, and from that, sanitize the group names.

This is a great moment to add UI tests :) .

Dotin output is messy right now, UI tests would also help improvements in that aspect.