Added cDevice::Flush()

CONTRIBUTORS

@@ -854,6 +854,8 @@ Reinhard Nissl <rnissl@gmx.de>
  when using other libraries that also implement a function by that name
  for reporting a bug in handling ':' characters in channel names when reading
  channels.conf
+ for adding cDevice::Flush() to make sure that all data in the video card's buffers
+ has been processed
 
 Richard Robson <richard_robson@beeb.net>
  for reporting freezing replay if a timer starts while in Transfer Mode from the