lib: Utilize smaps in the idl.

String to string maps are used all over the Open vSwitch database.
Before this patch, they were implemented in the idl as parallel
string arrays.  This strategy has proven a bit cumbersome.  With
this patch, string to string maps are implemented using the smap
library.

Signed-off-by: Ethan Jackson <ethan@nicira.com>

python/ovs/db/types.py

@@ -450,6 +450,11 @@ class Type(object):
     def is_map(self):
         return self.value is not None
 
+    def is_smap(self):
+        return (self.is_map()
+                and self.key.type == StringType
+                and self.value.type == StringType)
+
     def is_optional_pointer(self):
         return (self.is_optional() and not self.value
                 and (self.key.type == StringType or self.key.ref_table_name))