[as3] Reset track entry mix blend, fix stepped curves, see #1903

spine-as3/spine-as3/src/spine/SkeletonJson.as

@@ -957,7 +957,7 @@ package spine {
 		static private function readCurve(curve : Object, timeline : CurveTimeline, bezier : int, frame : int, value : Number, time1 : Number, time2 : Number,
 			value1 : Number, value2 : Number, scale : Number) : int {
 			if (curve == "stepped") {
-				if (value != 0) timeline.setStepped(frame);
+				timeline.setStepped(frame);
 				return bezier;
 			}
 			var i : int = value << 2;

spine-as3/spine-as3/src/spine/animation/AnimationState.as

@@ -605,6 +605,7 @@ package spine.animation {
 			entry.interruptAlpha = 1;
 			entry.mixTime = 0;
 			entry.mixDuration = last == null ? 0 : data.getMix(last.animation, animation);
+			entry.mixBlend = MixBlend.replace;
 			return entry;
 		}