Fix usage of configuration variables
Drop URL to release notes from script header
Improve error handling for update-locale

Set absolute path to /usr/sbin/update-locale to make sure
the binary can be accessed no matter what's inside $PATH
and if it's not present inform user about it, but do not fail
because the locales-all package might be installed and it doesn't
provide the /usr/sbin/update-locale binary.
Release new version 0.59