more total spline stuff

Author: liqyn

src/main/java/com/github/mittyrobotics/pathfollowing/QuinticHermiteSplineGroup.java

@@ -250,4 +250,14 @@ public void updateSplineLength(int index, double prevLength) {
         length -= prevLength;
         length += splines.get(index).getLength();
     }
+
+    /**
+     * Updates the total spline length
+     */
+    public void updateSplineLength() {
+        length = 0;
+        for(QuinticHermiteSpline spline : splines) {
+            length += spline.getLength();
+        }
+    }
 }