Update copyright year in packages
innoextract: Fix bogus date in RPM spec file
arx-libertatis: Use SDL 2 on openSUSE 13.1+
Update Ubuntu release information
Adapt deb.prepare to dpkg-buildpackage change

The GPG command can no longer be a shell one-liner.
arx-libertatis: Update minimum dep versions
Generate sha512 checksums for downloads
Include build IDs in compiled binaries
Add README file