Many small improvements, bug fixes, and build system fixes for newer systems that have both qt4 and qt5.

include/ChunkReader.h

@@ -58,6 +58,7 @@ namespace openshot
 		FFmpegReader *local_reader;
 		chunk_location previous_location;
 		ChunkVersion version;
+		tr1::shared_ptr<Frame> last_frame;
 
 		/// Check if folder path existing
 		bool does_folder_exist(string path);

include/FFmpegReader.h

@@ -92,6 +92,7 @@ namespace openshot
 		AVPacket *packet;
 		AVPicture *pFrame;
 		bool is_open;
+		bool is_duration_known;
 
 		bool check_interlace;
 		bool check_fps;