Fix typo in readme example code
Fix bug that would let certain incorrect entries to match captchas pass as valid.

Type cast would let certain math captchas pass when incorrect answers were submitted (e.g. for captcha 3 x 1, 3-555 would be an acceptable answer because "3-555" would get cast to int and drop off the "-555" portion of input)
Fix backslashes in rendered html on windows
fix mail validation for x-y@z.org ("-")
Release 3.5.4