KMail Tagging Patch

I decided to finally publicize this patch a bit more, since I am using it and am quite happy. This is a patch on top of the KDE 3.5.1 code for KMail. It introduces custom tagging support for emails. Since KDE is in feature freeze, I decided to maintain it as a patch until a merge into the next version is viable.

Here is what the patch adds:
* Ability to tag emails (with possibly more than one tag)
* Changing the appearance of message headers (font and text color) according to the message's tags.
* Configuration of tags through a new tab called "Message Tags" on the "Configure KMail->Appearance" configuration page.
* You can add toolbar buttons for easy tagging.
* You can assign shortcuts to tags.
* Tagging through the right-click menu.
* Quick filtering using the combobox for "status" filtering. See the screenshot.

For bugs and problems, feel free to send an email.

Disclaimer: This patch is still in experimental state. So before trying, it is strongly advised that you backup your emails and settings. ( usually in ~/.kde/share/apps/kmail and ~/.kde/share/config/kmailrc )

0.2.6 : Minor fix - added check for null pointers