Cannot compile in release mode

If compiled in release mode such as App Store or Ad Hoc deployments, SlideMenuControllerSwift doesn't work because the linker doesn't find symbols, etc.

Extensions such as these cause syntax errors like “ambiguous use” if the Swift file is being directly copied into the project.
```swift
@interface UIViewController (SWIFT_EXTENSION(SlideMenuControllerSwift))
- (SlideMenuController * _Nullable)slideMenuController;
- (void)addLeftBarButtonWithImage:(UIImage * _Nonnull)buttonImage;
- (void)addRightBarButtonWithImage:(UIImage * _Nonnull)buttonImage;
- (void)toggleLeft;
- (void)toggleRight;
- (void)openLeft;
- (void)openRight;
- (void)closeLeft;
- (void)closeRight;
- (void)addPriorityToMenuGesuture:(UIScrollView * _Nonnull)targetScrollView;
@end
```
Curiously, everything works just fine within the demo project; and project settings seem to be identical.

Any ideas? Maybe compiler optimized things away?