Merge branch 'cython-base' to add basic Cython Adjacency Mapping grap…

…h (see issue #2)

.gitattributes

@@ -0,0 +1,2 @@
+# ignore c files generated by Cython
+*.c linguist-generated=true

graphi/abc.py

@@ -544,7 +544,6 @@ class AdjacencyList(dict, abc_collection.MutableMapping):
     __slots__ = ('__weakref__',)
 
 
-@AdjacencyList.register
 class AdjacencyView(GraphView):
     """
     View on the adjacency of edges for a node in a graph
@@ -572,3 +571,6 @@ def __len__(self):
 
     def __contains__(self, node):
         return edge.Edge(self._node, node) in self._graph
+
+
+AdjacencyList.register(AdjacencyView)

graphi/types/cython_graph/__init__.py

@@ -0,0 +1,19 @@
+from ...abc import Graph as GraphABC
+from ..decorator import boundable, undirectable
+
+from .plain_graph import CythonGraph as _PlainGraph
+
+
+@boundable
+@undirectable
+class CythonGraph(GraphABC):
+    """
+    Optimised Cython Graph Implementations
+
+    .. note:: This is an abstract class that merely picks the most suitable implementation.
+    """
+    def __new__(cls, *args, **kwargs):
+        return _PlainGraph(*args, **kwargs)
+
+
+CythonGraph.register(_PlainGraph)