move and check in OpenFlow protocol modules

Move all the protocol code out of the oftest package and into a of10 package to
prepare for supporting more OpenFlow versions.

The generated code is now checked-in to make it simpler to use OFTest.

Backwards compatibility with out of tree tests is maintained by aliasing the
old module names. The basic test module has been changed to use the new API.
diff --git a/tools/munger/scripts/error_gen.py b/tools/munger/scripts/error_gen.py
index 83850f5..b1f360e 100644
--- a/tools/munger/scripts/error_gen.py
+++ b/tools/munger/scripts/error_gen.py
@@ -5,7 +5,7 @@
 
 import re
 import sys
-sys.path.append("../../src/python/oftest")
+sys.path.append("../../src/python/of10")
 from cstruct import *
 from class_maps import class_to_members_map