Beat effects windows on the Mac into submission

This should resolve all concerns with the effects windows like:

1)  Dropping behind the project window
2)  Obscuring other dialogs
3)  Keyboard cycling among the active windows
4)  Clicking twice to do something in another window
    NOTE:  VST effects with a Cocoa overlay still require it.
           Examples are Blue Cat and GRM.

This does tie an open effect to its parent project, but that should
be okay.  We'll need to verify that again once we start to allow
multiple open effects dialogs at once.



git-svn-id: http://audacity.googlecode.com/svn/audacity-src/trunk@13676 47890b92-0858-11df-a26f-8b716316a5bc