Common trunk upstream

[kareltucek]

Here are remaining updates which have accumulated since the original common_trunk PR.

Recommended order of merging is:

• (optionally - merge common_tunk into stock master)
• merge rest of the PRs into common_trunk (or stock master) one by one.
• merge this PR into common_trunk (in order to "feature freeze" it for testing, and after all others so that you can review the diff without the other PRs being in way)
• test common_trunk for as long as you wish
• merge common_trunk (now including feature freezed common_trunk_upstream) into stock master

(Order of merging between common_trunk and stock master does not matter - If you prefer merging into stock master directly, feel free to. common_trunk is meant to be a "staging ground" specifically for stock master merges.)

[mondalaci]

Please open a PR in https://github.com/UltimateHackingKeyboard/firmware

[kareltucek]

Please open a PR in https://github.com/UltimateHackingKeyboard/firmware

Meaning that I can close all these four?

[mondalaci]

Yes, I'd appreciate it if you could recreate the four PRs in https://github.com/UltimateHackingKeyboard/firmware