Library export to file requires a library container but when pasting, we
paste into an existing library, so we need to skip the library header.
Long term solution would be to allow pasting library with multiple
symbols into existing library
Fixes https://gitlab.com/kicad/code/kicad/-/issues/19688
Recommendation is to avoid using the year nomenclature as this
information is already encoded in the git repo. Avoids needing to
repeatly update.
Also updates AUTHORS.txt from current repo with contributor names
It is useful mainly in Pcbnew, to import a logo from Bitmap2component,
without the constraint to create a file and use the fp editor.
Also a bit of cleanup code.
Fixes: lp:1820829
https://bugs.launchpad.net/kicad/+bug/1820829
