Add testcase for sibling modules.

Closes PR 13155.
Improve type of expt since inference is bad.

Closes PR 13383.
Reimplement for*/list: in TR so that it works.

Closes PR 13253.
Remove dependency on GUI libraries.
racket/cmdline: fix problem with arity checking

Extra normalization due to 59b1e32fe9 exposed the bug.
bring code to old state, make consistent with docs, Closes PR 13642 again