Add edge with two hinges to top edge param and edge descriptions

boxes/__init__.py

@@ -256,7 +256,7 @@ class Boxes:
             elif arg == "top_edge":
                 self.argparser.add_argument(
                     "--top_edge",  action="store",
-                    type=ArgparseEdgeType("ecESi"), choices=list("ecESi"),
+                    type=ArgparseEdgeType("ecESik"), choices=list("ecESik"),
                     default="e", help="edge type for top edge")
             else:
                 raise ValueError("No default for argument", arg)

boxes/edges.py

@@ -19,9 +19,11 @@ import math
 import inspect
 
 def getDescriptions():
-    return {edge.char : edge.description for edge in globals().values()
+    d = {edge.char : edge.description for edge in globals().values()
          if inspect.isclass(edge) and issubclass(edge, BaseEdge)
          and edge.char}
+    d['k'] = "Straight edge with hinge eye (both ends)"
+    return d
 
 class BoltPolicy(object):
     """Abstract class