Add menu and prepare extension

Hello,

I really liked you project but I have a need to export to html so I made small changes that:

 * will allow it to be extended (file and function structure and naming)
 * added a menu to make it easy to re-export after editing

I already made the basic html export but will not be able to commit it today for there is some cleaning up to do still. Will do it tomorrow I hope.

thanks!