Vacuum 2020: Clean up the issue tracker

[dcodeIO]

There are 82 issues (incl. this one) and 39 pull requests as of today. From my experience, these numbers just keep growing over time, making it even harder to resolve them eventually, so I'd like to suggest that we make a concentrated effort starting today to either close what's outdated, fix low-hanging fruit or re-triage what should remain open.

To keep track of progress, let's start from the bottom and make at least a comment on each linking to this issue so we get some history below. Also going to create a vacuumed label we can apply to issues we already checked, that we can remove again once this issue is closed.

[dcodeIO]

Not yet done, but there's progress. So far, we are down to 63 issues (82-19) and 20 pull requests (39-19) (already subtracted one pending PR that closes one issue, itself and another PR).

[dcodeIO]

From what I can tell most of what can be done has been done. There might be a few more issues we may be able to close, but there was some uncertainty on the initial check, and I'm leaning towards not pressing it any further so we don't end up closing something that should remain open :) Concluding this year's vacuum hereby.