I'm sorry to say that any big updates of basicbuilder will have to wait. I've been accepted in the google summer of code and will be making an app to graph differential equations. This will take all(/most) of the time I write calc programs in. Thus I will keep the idea to add a plugin system as a potential project for the future. If anyone else wants to make the plugin system, feel free to mail me. I will send you the code and mentor your work if you want to.