Since I am striving for closer connection between my task management, my
mail suite and my calendar appointments, it makes sense to unify all
'office' tasks into the single office module instead of keeping
taskwarrior outside of it.
Timewarrior now looks for its data directory in `XDG_CONFIG_HOME`
instead of the home directory. This is a little better than nothing, but
does not separate the configuration and data files from each other yet.
Data *should* be lying in `XDG_DATA_HOME` but the data directory can not
be separated since it relies on a single env var `TIMEWARRIORDB`.