Combine unit and research functions

aoe/production.py

@@ -1,3 +1,5 @@
+from collections import defaultdict
+
 from aoe.types import *
 
 
@@ -7,7 +9,7 @@ class Production():
 
     # assumes for now each unit can be built in only one type of building
     def __init__(self):
-        self.building = {
+        self.building = defaultdict(None, {
                          Units.VILLAGER: Buildings.TOWNCENTER,
                          Units.TRADECART: Buildings.MARKET,
                          Units.SPEARMAN: Buildings.BARRACKS,
@@ -93,4 +95,4 @@ class Production():
                          Research.LOOM: Buildings.TOWNCENTER,
                          Research.SAPPERS: Buildings.CASTLE,
                          Research.BOMBARDTOWER: Buildings.UNIVERSITY,
-                        }
+                        })