Filter tips aren't shown in Formatting guidelines

Issue Summary

With "Encode email addresses" included in one of my input formats, the system-generated Formatting guidelines for that format don't currently include any statement about what invisimail will do, e.g. "Email addresses will be obfuscated in the page source."

Invisimail does include a filter tip, but it's never shown because it's wrapped in if ($long) { ... }. The attached patch fixes this, and also provides a shorter filter tip text. You could use my text not, but the main thing is to return a filter tip whether or not $long is set.

Thanks,
Andrew.