Create an ordering for everything

In order to make layouts more reproducible
Also add pattern.sort() and file.utils.preflight_check()

optionally don't sort elements
elements aren't re-ordered that often, sorting them is slow, and the
sort criteria are arbitrary, so we might want to only sort stuff by name

masque/shapes/shape.py

@@ -42,6 +42,14 @@ class Shape(PositionableImpl, Rotatable, Mirrorable, Copyable, Scalable,
     #
     # Methods (abstract)
     #
+    @abstractmethod
+    def __eq__(self, other: Any) -> bool:
+        pass
+
+    @abstractmethod
+    def __lt__(self, other: 'Shape') -> bool:
+        pass
+
     @abstractmethod
     def to_polygons(
             self,