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
Merge branch 'master' into pyloxi-1.3

Also added ofp_hello_elem_type to standard-1.3.

Conflicts:
	loxi_front_end/translation.py
Merge pull request #2 from rlane/pyloxi-1.3

Initial PyLoxi 1.3 work
Fix code generation on 32 bit operational systems.
Python types are different on 32 and 64 bit systems for equal values.
e.g: The value 0xffffffff is considered long on 32 bit systems and
int on 64 bit systems.
Merge pull request #6 from ederlf/master

Fix code generation on 32 bit systems.
pyloxi: add basic test cases for of11 and of12

Also fixes minor bugs when importing those modules, and adds a check-py target
to run all the unit tests against the generated code.
pyloxi: add loxi.version_names
pyloxi: include all members in OFClass.members

This preserves ordering, which is important because we can't rely on the offset
field for sorting (it may be -1).

The newly passing show() tests are due to the side effect of removing type
fields from pretty printing.
pyloxi: add padding as its own member type

Also remove it from pretty-printing.
pyloxi: move version-independent utility code to a new file

Also adds a test for unpack_list.
pyloxi: add OFReader class

This will be used for unpacking messages instead of the current strategy which
depends on fixed offsets.
pyloxi: rewrite deserialization to use OFReader
pyloxi: support field length members

These are members whose value is the length of another member. This is used in
OpenFlow for variable length members in the middle of a message. Variable
length members at the end do not need a field length member because their
length is implicit. The field length members must come before, but not
necessarily immediately before, the field they refer to.

The only place this was used in OF 1.0 was in packet_out. Now that this is
gnerically supported we can remove the special case code for packet_out.
pyloxi: alias of11/of12 matches
pyloxi: support (only) empty 1.2/1.3 matches
pyloxi: fix OXM lengths

The length field only includes the payload, not the header.