More exact testing for scaling/flipping in AffineTransform and only combine transforms when not equal in ForwardExtentCopy

- Fixes #1162
 - Also fixes rotation in x/z axes

worldedit-core/src/main/java/com/sk89q/worldedit/function/operation/ForwardExtentCopy.java

@@ -279,6 +279,8 @@ public class ForwardExtentCopy implements Operation {
     public Operation resume(RunContext run) throws WorldEditException {
         if (currentTransform == null) {
             currentTransform = transform;
+        } else if (!currentTransform.equals(transform)) {
+            currentTransform = currentTransform.combine(transform);
         }
         if (lastBiomeVisitor != null) {
             affectedBiomeCols += lastBiomeVisitor.getAffected();
@@ -406,7 +408,6 @@ public class ForwardExtentCopy implements Operation {
             }
 
             if (transExt != null) {
-                currentTransform = currentTransform.combine(transform);
                 transExt.setTransform(currentTransform);
             }
 

worldedit-core/src/main/java/com/sk89q/worldedit/math/transform/AffineTransform.java

@@ -306,13 +306,13 @@ public class AffineTransform implements Transform, Serializable {
             return true;
         }
         // Check for flip-and-rotate
-        if (vector.getX() != 0 && vector.getY() != 0 &&  m01 != 0 && m10 != 0) {
+        if (vector.getX() != 0 && vector.getY() != 0 && ((m01 < 0 && m10 < 0) || (m01 > 0 && m10 > 0))) {
             flip = true;
         }
-        if (vector.getX() != 0 && vector.getZ() != 0 &&  m02 != 0 && m20 != 0) {
+        if (vector.getX() != 0 && vector.getZ() != 0 && ((m02 < 0 && m20 < 0) || (m02 > 0 && m20 > 0))) {
             flip = !flip;
         }
-        if (vector.getY() != 0 && vector.getZ() != 0 && m12 != 0 && m21 != 0) {
+        if (vector.getY() != 0 && vector.getZ() != 0 && ((m12 < 0 && m21 < 0) || (m12 > 0 && m21 > 0))) {
             flip = !flip;
         }
         return flip;