"needs testing" label

Nobody has claimed this yet.

There's the "needs testing" label for PRs. Change requests:

* The label is unclear: Does the OP need a tester who looks at the code while testing (**whitebox tester**) or one who does not look at the code while testing (**blackbox tester**)? Both could be needed. Maybe the functional code-reader should define what parts of the code need whitebox testing, if any (e.g. another point on ["Reviewing Pull Requests"](https://github.com/LMMS/lmms/wiki/Reviewing-Pull-Requests))?
* Any idea how we can offer a **task lists for potential blackbox testers**? That way, testers who want to help can easily find PRs. It's actually just a filter "needs testing" on all of our PRs, but I guess many testers don't even know that we have such a list of open PRs... We could open a meta-issue and pin it, but not sure if this will reach many testers.

One reason I ask this is because we have only few devs, but many testers (actually all issue writers, and we have *many* issues).

Start with the issue's proposed meanings for the "needs testing" label and the linked "Reviewing Pull Requests" wiki page. Define the testing terminology and decide how potential blackbox testers should find relevant pull requests, with the label or a pinned meta-issue providing an actionable, discoverable task list.

Written by the indexing model from the issue text.