Cleaned up namespace handling.

A Namespace object is now guaranteed unique.
This cleaned up some old workarounds and latent bugs.

Change-Id: Ic3f12d89947871b03b2c449ba51b3186f953adde
Tested: on Linux.
Bug: 21336857

tests/MyGame/InParentNamespace.py

@@ -0,0 +1,22 @@
+# automatically generated by the FlatBuffers compiler, do not modify
+
+# namespace: MyGame
+
+import flatbuffers
+
+class InParentNamespace(object):
+    __slots__ = ['_tab']
+
+    @classmethod
+    def GetRootAsInParentNamespace(cls, buf, offset):
+        n = flatbuffers.encode.Get(flatbuffers.packer.uoffset, buf, offset)
+        x = InParentNamespace()
+        x.Init(buf, n + offset)
+        return x
+
+    # InParentNamespace
+    def Init(self, buf, pos):
+        self._tab = flatbuffers.table.Table(buf, pos)
+
+def InParentNamespaceStart(builder): builder.StartObject(0)
+def InParentNamespaceEnd(builder): return builder.EndObject()