- 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.
- add an option to select what button should be selected when the
partitioning module is started; TODO: the actual functionality is
**not** implemented.
- drop the previously suggested name, which didn't get beyond the
comments-in-the-config-file stage (but which intended to do the
same things as this one)
- add option to schema already, even if it's not implemented.
See #1297
FIXUP conf
