[TIMOB-14342] iOS: UI.iPhone.NavigationGroup - Support custom window transitions/animations

Most apps will want to incorporate iOS' standard Navigation Bar in their apps. One of two ways to include the Navigation Bar is by using a NavigationGroup to wrap your windows. Opening (or closing) a new window either uses the default left-right sliding animation, or no animation at all. I know that the underlying, native UINavigationController works identically in this regard. Interestingly, in native land people seem to be having found ways to use custom animations for window transitions nonetheless. I would very much like to have this flexibility in Titanium as well. My Cocoa/ObjectiveC knowledge is lacking, so I don't know how solid these workarounds are, but below is a list of some of the results that came up while searching the web: * http://stackoverflow.com/questions/2215672/how-to-change-the-push-and-pop-animations-in-a-navigation-based-app * http://stackoverflow.com/questions/1406037/custom-animation-for-pushing-a-uiviewcontroller * http://stackoverflow.com/questions/2001466/changing-the-animation-for-uinavigationcontroller-navigationbar * https://gist.github.com/nvln/1831040 These constructions all either seem to use mechanisms that are not supported, or properties that are not exposed via Titanium. Perhaps there is more optimal way of introducing custom transitions, I leave that to you. My questions is: Would it be possible for you to implement a way for us developers to get custom transitions into our apps, while still using the NavigationGroup?