Release 0.15.13

Release v0.15.8

- remove pre-systemd default groups for user creation
- update mkinitcpio hooks
- make user-shell configuration available via profile.conf
- support CAL v3.2.1+
- introduce -d flag to set compression level during ISO creation
- support pacman 5.1 series
- restore functionality to define ISO size via profile.conf
- use short url for webseed on torrents

buildiso: use grub on install media

remove plymouth
remove aufs support

fix thus config for sonar