Allow song timing to be used when playing.

Admitedly, this may not be the best implementation.
As usual, if you can do better, go for it.

src/ScreenEdit.cpp

@@ -2354,12 +2354,16 @@ void ScreenEdit::TransitionEditState( EditState em )
 
 		case STATE_PLAYING:
 			AdjustSync::HandleSongEnd();
+			if (!GAMESTATE->m_bIsUsingStepTiming)
+				GAMESTATE->m_pCurSteps[PLAYER_1]->m_Timing = backupStepTiming;
 			if( AdjustSync::IsSyncDataChanged() )
 				ScreenSaveSync::PromptSaveSync();
 			break;
 
 		case STATE_RECORDING:
 			SetDirty( true );
+			if (!GAMESTATE->m_bIsUsingStepTiming)
+				GAMESTATE->m_pCurSteps[PLAYER_1]->m_Timing = backupStepTiming;
 			SaveUndo();
 
 			// delete old TapNotes in the range
@@ -2410,6 +2414,12 @@ void ScreenEdit::TransitionEditState( EditState em )
 		GAMESTATE->UpdateSongPosition( fSeconds, GetAppropriateTiming(), RageZeroTimer, true );
 
 		GAMESTATE->m_bGameplayLeadIn.Set( false );
+		
+		if (!GAMESTATE->m_bIsUsingStepTiming)
+		{
+			backupStepTiming = GetAppropriateTiming();
+			GAMESTATE->m_pCurSteps[PLAYER_1]->m_Timing = GAMESTATE->m_pCurSong->m_SongTiming;
+		}
 
 		/* Reset the note skin, in case preferences have changed. */
 		// XXX

src/ScreenEdit.h

@@ -251,6 +251,13 @@ protected:
 
 	BitmapText		m_textInputTips;
 	
+	/**
+	 * @brief Keep a backup of the present Step TimingData when
+	 * entering a playing or recording state.
+	 *
+	 * This is mainly to allow playing a chart with Song Timing. */
+	TimingData		backupStepTiming;
+	
 	/** @brief The current TapNote that would be inserted. */
 	TapNote			m_selectedTap;