Remaining implementations of JavaScript's Math functions (except sin/cos/tan), both double (Math) and single (Mathf) precision, ported from musl incl. tests from libc-test, plus some changes to match JS semantics. Also binds fmod to `%` and pow to `**`.
This now checks that distribution files are unmodified and fails otherwise. Also checks if the author is present in the NOTICE file and prints the result, but as email addresses may vary, does not hard-fail.
