wperl is necessary to get rid of the console window,
which is merely one of several issues with the PAR Packer-based
ExifTool bundle used in the last commit.
The Perl installation could be heavily trimmed down,
but it seems to require a very manual process.
- Fix launching of subprocesses (missing gspawn helpers).
- Discard unused GSettings schemas.
- Make the program find its user guide.
- Bundle a somewhat suboptimal version of ExifTool.
