joNavbar can't be extended

[ukabu]

There is an issue with joNavbar that prevent it from being extended (subclassed).

The listener for the back button is a function called back. But in the constructor function, it is replaced by the back property which hold the reference to the joBackButton.

The code works because when adding the event listener, the reference to the function has not be called yet, but this cause issues when extending the joNavbar.

The listener should be named goBack instead of back (or any other name that is not back).

[davebalmer]

Good catch! Moving this weekend, will get on it next week unless someone else gets to it first.