small pattern and fix circle arc

grid/test/test_pattern.py

@@ -1,7 +1,7 @@
-from grid.ui.pattern import Pattern
+from grid.ui.pattern import LargeUltimaPattern
 
 
 class TestPattern:
     def test_position(self):
-        p = Pattern(0, 0)
+        p = LargeUltimaPattern(0, 0)
         assert len(p.childItems()) > 0