Add some failing tests

Hey, I noticed that this library isn't exactly implementing the tripcode algorithm correctly, so I added some failing tests to help you out.

  - A corrected output for `!@#$%^&*()`. This string is longer than the allowed length for tripcode passwords (8), so it should return the same result as `!@#$%^&*`.
  - A simple. but failing, test for `f}E`.
  - Symbols like the copyright symbol `©` are supposed to be ignored but are not in this library
  - Weird symbols like [`U+8A1B CJK UNIFIED IDEOGRAPH-8A1B`](http://codepoints.net/U+8A1B) do not yield the correct tripcode.