update proposal to lang DE

Update OpenBoard_sk.ts

fixed my own typo

This reverts commit 7dc58b7e.

This reverts commit adb884c8.

This reverts commit 410d0ff1.

added some relinks in Homebrew libs (absolute paths refering to other libs ... homebrew 2.0 issue ? osx upgrade issue ? xcode linker issue ?

Distro agnostic ffmpeg version test

OpenBoard.css: Add background color to QMenu, QPushButton and QComboBox

Fix wrong German translation: "Kompass" -> "Zirkel"

This reverts commit 63e5e8ec.

Fixes ui with dark system themes

reuse last used color for newer text boxes (only if applied globally) + recolor text boxes on background changes (white text becomes black and black text becomes white (like for polygons))

fixed an issue where font family styles of a block with the same font family were lost when changing size

improved scrolling behavior (ensure visible) + fixed issues on drag and drop due to constantly regenerated thumbnails...

In German, "Kompass" is the navigational instrument. The drawing tool is called "Zirkel."