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/DEVELOPING b/DEVELOPING
index ff391e4..ea6945a 100644
--- a/DEVELOPING
+++ b/DEVELOPING
@@ -44,7 +44,8 @@
 
     1.  If you change any of the code generation scripts in
     tools/munger/scripts you must re-run make -C tools/munger to
-    regenerate the OpenFlow message classes.
+    regenerate the OpenFlow message classes. Make sure you
+    commit the generated code.
 
 Adding Your Own Test Cases
 ++++++++++++++++++++++++++