Provide a way to create nested bundles

Issue #63 new
Ronald Oussoren
repo owner created an issue

As noted by Micheal McCracken in issue #13:

To add some info - I have both problems :)
I'd like to build a main app bundle that contains both a non-GUI 'tool', 
and a helper app that shows a window (but has LSUIElement=1)

So from this, it looks like I'll need multiple calls to setup() to build 
the two apps.

The embedded helper app currently requires scripting outside of py2app, it would be nice if there was a way to specify this within the py2app configuration, for example:

           'name': 'BasicApp',
           'script': '',
            'name': 'BackgroundHelper',
            'host': 'BasicApp',

The chosen solution should also work with plugin bundles, and preferable would make it easy to add native code extensions later on. That is, I'd like to be able to add an (Objective-)C QuickLook plugin to a python app and control the entire build using py2app.