add Glyph.appendContour method

for compat with defcon API (#41)

src/ufoLib2/objects/glyph.py

@@ -6,6 +6,7 @@
 from fontTools.pens.pointPen import PointToSegmentPen, SegmentToPointPen
 
 from ufoLib2.objects.anchor import Anchor
+from ufoLib2.objects.contour import Contour
 from ufoLib2.objects.guideline import Guideline
 from ufoLib2.objects.image import Image
 from ufoLib2.pointPens.glyphPointPen import GlyphPointPen
@@ -148,6 +149,13 @@ def appendGuideline(self, guideline):
             guideline = Guideline(**guideline)
         self._guidelines.append(guideline)
 
+    def appendContour(self, contour):
+        if not isinstance(contour, Contour):
+            raise TypeError(
+                f"Expected {Contour.__name__}, found {type(contour).__name__}"
+            )
+        self.contours.append(contour)
+
     def copy(self, name=None):
         """Return a new Glyph (deep) copy, optionally override the new glyph name.
         """