Add parameters to BackgroundChange: fRate, bFadeLast, bRewindMovie, bLoop.

I don't like how this changes the syntax for the #BGCHANGES tag in an SM file.  I will think more about this - it's important to finalize it quickly.

stepmania/src/NoteField.cpp

@@ -309,7 +309,17 @@ void NoteField::DrawPrimitives()
 		{
 			if(aBackgroundChanges[i].m_fStartBeat >= fFirstBeatToDraw &&
 			   aBackgroundChanges[i].m_fStartBeat <= fLastBeatToDraw)
-				DrawBGChangeText( aBackgroundChanges[i].m_fStartBeat, aBackgroundChanges[i].m_sBGName );
+			{
+				const BackgroundChange& change = aBackgroundChanges[i];
+				CString sChangeText = ssprintf("%s\n%.0f%%%s%s%s",
+					change.m_sBGName.GetString(),
+					change.m_fRate*100,
+					change.m_bFadeLast ? " Fade" : "",
+					change.m_bRewindMovie ? " Rewind" : "",
+					change.m_bLoop ? " Loop" : "" );
+
+				DrawBGChangeText( change.m_fStartBeat, sChangeText );
+			}
 		}
 
 		//