Comment changes/updates
* DanboTools.cs: Added missing parameter documentation.

* HtmlHelp.cs: Added a new charsetReplace for UTF-8.
Moving the Booru- and ChanHandler code into their own files.
Add support for Gelbooru. This only translates to printing a warning
when it has one or more of the Warning Tags.
This is because the API doesn't give us much to work with, just a
string of all tags - not seperated by artist, character or copyright.