This patch removes chasquid-userdb and adds a more generic and extensive
chasquid-util, that supports various operations on user databases as well as
aliases lookups.
The code is not very pretty but for now I took a more practical approach, the
tool is ancillary and can be tidied up later.
aliases databases can be very useful, so this patch adds a package to parse
and resolve aliases.
It uses an existing, well known and widely used format for aliases, although
it doesn't necessarily match 100% any existing implementation at the moment.
