Rejoice at the new get_message

get_message is now python, so libgms is dead. messaged was never
packaged in Debathena, so remove it from the superrepo.
Add locker-support to superrepo
Remove cviewd from super-repository

cviewd was never packaged for Debian and hence does not need to be
included into the super-repository
Move debathena-common to the appropriate path
Remove debathena-libss and debathena-libreadline

Those are equivs packages on which nothing in the super-repository
build-depends anymore.