Extracting content in the query pane

Pressing the "Go" button sends a request to the server with the contents
of the form.
Dynamic queries

Created the function build_query to accomodate the random requests from
the client. Refactored the existing static queries to rely on it too, just
to avoid having all these hard-coded queries everywhere.
Form cleanup

Added submit-on-enter to the form. Also returning an empty object when the
submission is the empty form. The form itself needs validation too, but
the server is more reliable.