Regex octal escape sequence bug

[helixbass]

While reading lexer.coffee spotted a hole in the validateEscapes() logic: if it encounters a valid "INVALID_ESCAPE" (eg \1) inside a regex interpolation-free section then it fails to check the rest of the section for actually invalid escapes. So eg /\1\01/ should fail but instead generates /\1\x001/

Will submit a fixing pull request momentarily