Updating references to frame number / position to long int, there were still quite a few old "int" declarations, which limits the length of frame number. Also, updated precision of KeyFrames to use double (instead of float) for higher precision, which fixed lots of issues with very long videos (since our FrameMapper used a KeyFrame object to create a map to new frames)

src/Frame.cpp

@@ -466,7 +466,7 @@ void Frame::SetPixelRatio(int num, int den)
 }
 
 // Set frame number
-void Frame::SetFrameNumber(int new_number)
+void Frame::SetFrameNumber(long int new_number)
 {
 	number = new_number;
 }