table features properties should be a list
use t type in message for multipart
Table Features Instruction only parse the header
Table Features Action only parse the header
port_id(0x04): make invalid port printable
port_id(0x04): properly check phyiscal port range

OCaml does not provide unsigned types. The 0xffffff00l constant was
wrapping around to a negative value, causing the function to report that
all physical ports as invalid. Converting to Int64.t avoids the
wrapping.
Merge pull request #154 from frenetic-lang/port_id

Fix port_id checking
Change type name to be more understandable
rename ActionType to ActionTypeMap to be more understandable
activity: record activity on echo reply
activity: remove unused optional argument

This was not part of the public interface.
activity: rework handshake/activity distinction

Treat the handshake state as something separate and orthogonal to
tracking activity. Now it's possible to detect an idle connection that
has not completed a handshake and kill it if necessary.
activity: record activity for all messages
fix failed test:
typo error in size of actionHdr
Merge pull request #153 from fugitifduck/tableFeat

Table feat
stale: remove old, unused .mli files
mli: Add interface file for SDN_OpenFlow0x04
Merge pull request #159 from frenetic-lang/stale

stale: remove old, unused .mli files
activity: Make echo the first stage of the pipeline

According to the OpenFlow specifications, controllers should implement
the echo response at the lowest-level possible.
mli: note that VLAN ops are exposed but not public

Related to #163.