Expose public screenshot method

This is useful when trying to connect a compose view that is using a custom UIViewController via the delegate

Classes/BITFeedbackManager.h

@@ -267,6 +267,15 @@ typedef NS_ENUM(NSInteger, BITFeedbackObservationMode) {
  */
 @property (nonatomic, readwrite) BOOL showFirstRequiredPresentationModal;
 
+
+/**
+ Return a screenshot UIImage intance from the current visiable screen
+ 
+ @return UIImage instance containing a screenshot of the current screen
+ */
+- (UIImage *)screenshot;
+
+
 /**
  Present the modal feedback list user interface.
  */

Classes/BITFeedbackManager.m

@@ -198,6 +198,10 @@
 
 #pragma mark - Feedback Modal UI
 
+- (UIImage *)screenshot {
+  return bit_screenshot();
+}
+
 - (BITFeedbackListViewController *)feedbackListViewController:(BOOL)modal {
   if ([self isPreiOS7Environment]) {
     return [[BITFeedbackListViewController alloc] initWithModalStyle:modal];