Make "on" work with any event name

The documentation for the "on" function suggests it can be used to capture any event; to make this a reality we need to call DOMDelegator.listenTo with the event name at least once. (If it's already been called with the same name it does nothing.)
Add Native/Html.js changes to source file wrapper.js…

…so that they will persist when make.sh is run.
Merge pull request #10 from shaydon/generalise-on-2

[Reapply] Make "on" work with any event name