Library no longer works with action extension

[Kensen John]

The line
_applicationWindow = [[[UIApplication sharedApplication] delegate] window];
in IDMPhotoBrowser.m

assumes that the library is being used in an application when it might be being used in an action extension. Action extensions don't have access to the UIApplication singleton and won't compile when code includes those references.

Unfortunately this means the addition of this code precludes the use of IDMPhotoBrowser in action extensions, when it worked fine in action extensions before.

One possible solution is to include a preprocessor directive that checks a build flag and conditionally compiles code that is available only to applications. This is the approach that SVProgressHUD adopts.