generating ofp versions 1.1 through 1.3
adding other openflow versions
Merge branch '13-support' of git://github.com/jonstout/loxigen
LoxiGen: start generating pyloxi 1.3

Not all classes are fully implemented.
pyloxi: generate OXM classes
pyloxi: implement of_ipv6_t
LoxiGen: add OF 1.3 OF_HELLO_ELEM_TYPE group
pyloxi: support hello_elems