Merge pull request #12 from taikano/patch-6

Not an alternative, but introductory work

documents/musterloesung-db-2012-09-24/d2c1.2.sql

@@ -1,5 +0,0 @@
-SELECT f1.person2, f2.person2 
-    FROM FriendshipSymmetric f1
-    JOIN FriendshipSymmetric f2 ON f1.person1 = f2.person1
-    WHERE f1.person2 != f2.person2
-        AND f1.person1 = <id>;