Move Frege compilation into a subprocess to remove Leiningen from the classpath (avoids interaction between Frege annotations and some sonatype libraries). Also wires up stdout/stderr correctly.
Example of Clojure program calling into Frege functions.
Clarify that it is `:frege-source-paths` (plural) now.
Switch to plural source paths; clean up project.clj.
Add basic test example of Frege function exercised via clojure.test. Update README to show how to run tests.