Merge branch 'maint-0.2.4' into maint-0.2.5

Conflicts:
	src/or/or.h

changes/prop221

+  o Minor features:
+    - Stop sending the CREATE_FAST cells by default; instead, use a
+      parameter in the consensus to decide whether to use
+      CREATE_FAST. This can improve security on connections where
+      Tor's circuit handshake is stronger than the available TLS
+      connection security levels. Implements proposal 221.