This should avoid issues of the whole plugin not loading if OpenCV is
not available.
This approach should also work for possible future external
dependencies.
* adapt UI for i18n
* add placeWidgets() helper function to ease translation
* add hint about Transition Matrix plugin on Transition tab
* translate
* rework UI of file tab
* write status of plugin to scene info file
* fix MacOS CI issues due to QT deps
* adjust to new name of deps archive
* use MACOS_DEPS_VERSION instead of OSX_DEPS_VERSION
* disable python dependency during build