feature: connection aliases about usql

[kenshaw]

@rjbudzynski this has been requested more than once, and I have an overhaul coming that will add this functionality. In the interim, you can use variables, and set them in your .usqlrc:

$ cat ~/.usqlrc
\set MYURL postgres://user:pass@host
$ usql
Type "help" for help.

(not connected)=> \c :MYURL
error: pq: dial tcp: lookup host: no such host
(not connected)=> \echo :MYURL
postgres://user:pass@host
(not connected)=>

[rjbudzynski]

Thank you, very nice hint.

[kenshaw]

This is almost finished, and will be in the next major release.

[kenshaw]

This has been implemented.