Allow for saving the current drawing

Functionality is done except for the email part which is an open question(see the comments on the issue). I've added windows scripts for bundle, cover and test. If you don't want them I will remove them. 

A demo is available on http://mauritsmeijer.github.io/boxchareditor/
The data in Hello2 is broken. I have reached my request limit openkeyval, so I can't fix it atm.