Remove the Application.destroy method

This is a proposed incompatible API change: Remove the destroy() method from Application

This method is not ever being called except in applet mode, so the only impact is that applications that currently extend Application and override the destroy method will need to remove the method (or at least remove the @Override annotation).

Rich and I discussed this, and we don't see any reason for the destroy method at this time. We can always compatibly add it in a future release if we decide we need it.