Merge pull request bauerca#83 from scompt/child_reuse_crash

Only remove oldChild if it's not null

Author: bauerca

library/src/com/mobeta/android/dslv/DragSortListView.java

@@ -720,7 +720,9 @@ public View getView(int position, View convertView, ViewGroup parent) {
                 if (child != oldChild) {
                     // shouldn't get here if user is reusing convertViews
                     // properly
-                    v.removeViewAt(0);
+                    if (oldChild != null) {
+                        v.removeViewAt(0);
+                    }
                     v.addView(child);
                 }
             } else {