Open Sourced Toggle Headers Thunderbird extension

A long time ago I released the Toggle Headers extension for Thunderbird. I've kept it in a private git repository all this time (it might have started in a Subversion repository even).

This was way before I really got into open source. Recently, a member of the Thunderbirds Add-ons reviewer team sent in a fix and asked if I was willing to open source it to make contributions easier.

So I did open source it, and added a PR to fix compatibility with newer Thunderbird versions. I attributed this change to the reviewer who submitted the patch via email.

At the same time, it gave me a chance to create a script that allows me to build the add-on file. I had used ant before but given that it is only a ZIP file I wrote a small script in Python which makes it a lot easier to run.

Even though I don't use Thunderbird currently anymore, I find it important to keep maintaining the add-on. There are still a few users making use of it every day