[splittiming] Better variable name.

ArrowEffects had a minor change, but the intent isn't up yet.
It needs to be so that when you go from the editor to the chart
for playing in Song Timing, it doesn't use the Step Timing.

src/GameState.h

@@ -333,10 +333,10 @@ public:
 	// Edit stuff
 	
 	/**
-	 * @brief Is the editor making changes to Song timing or Steps timing?
+	 * @brief Is the game right now using Song timing or Steps timing?
 	 *
 	 * Different options are available depending on this setting. */
-	bool m_bIsEditorStepTiming;
+	bool m_bIsUsingStepTiming;
 	/**
 	 * @brief Are we presently in the Step Editor, where some rules apply differently?
 	 *