tests: Add more tests from The Reasoned Schemer

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
Get rid of lcons

Now that we switched to the cons branch, lcons is pointless (and buggy).
Changed all the lcons calls to cons.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>