offlineimap-mutt-cache: honor $XDG_CACHE_HOME
bogomark: honor $XDG_CACHE_HOME
bogomark: use XDG runtime directory if available
motd: honor $XDG_CACHE_HOME
lib.bash: quote $HOME where neccessary
lib: add Dir.pm
Dir.pm: read system-wide XDG config dirs
cap: use Dir.pm
Dir.pm: handle download => 'Downloads'
Dir.pm: simplify fallbacks, reject nonstandard names
twitter-backup: limit number of retries
dbus-name: reduce clutter
Revert "dbus-name: reduce clutter"

"(none)" is better aligned with normal output.

This reverts commit 63f754ffed09eef6b38bc8fbd1c88704f90f0744.