Expose overlayView on TOCropView.h to be able to customize from outside.

Author: Raúl Conesa

Objective-C/TOCropViewController/Views/TOCropView.h

@@ -47,6 +47,11 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @property (nonatomic, assign, readonly) TOCropViewCroppingStyle croppingStyle;
 
+/**
+ A semi-transparent grey view, overlaid on top of the background image
+ */
+@property (nonatomic, strong, readonly) UIView *overlayView;
+
 /**
  A grid view overlaid on top of the foreground image view's container.
  */