[WIP] [feature] UnusedUse - rewrite to use Tokens

UnusedUse - rewrite for use Tokens.
Work in progress

- [X] rewrite to use Tokens
- [X] fix #217
- [X] fix #317
- [X] fix #353
- [ ] set to run after `multiple_use` #480 (when merged!) and add testcase #481
- [ ] squash commits
Don't want to do it too soon if UnusedUse won't be merged - you never know ;)
But it was merged. I change it (of course with comment why - I hate to see non-zero priority without any info why...)