Tests via ASDF

Update README

Make prompt message a required argument

Print to *query-io* instead of *standard-output*

Started some tests

Fix

Experimental type parameter

Fix: input parser

Custom version of read-line that reads from *query-io*

Remove drakma dependency

Error color

More if-invalid argument parsing

Indentations. Housekeeping.

Simplify the api. Allow strings in :if-invalid

Create validator from a "spec"