- point to main Calamares site in the 'part of' headers instead
of to github (this is the "this file is part of Calamares"
opening line for most files).
- remove boilerplate from all source files, CMake modules and completions,
this is the 3-paragraph summary of the GPL-3.0-or-later, which has
a meaning entirely covered by the SPDX tag.
These additional pointers were introduced for translations,
and needed their own tricks to get lupdate to recognize the
strings. Using QCoreApplication::translate() removes the
need to a QObject to provide context. Drop the now-unneeded
parameters.
