support igtl::CommandMessage

[christiana]

Add support for the new v3 CommandMessage. Use PLUS to test against, as it uses the partly-v3-compliant IGSIO branch of OpenIGTLink.

[adamrankin]

Let me know how I can help.

[christiana]

@adamrankin thanks. I am getting back into the code now after a few months break. I'll implement the CommandMessage support tomorrow afternoon, using https://www.assembla.com/spaces/plus/subversion/source/HEAD/trunk/PlusLibData/ConfigFiles/Testing/PlusDeviceSet_OpenIGTLinkCommandsTest.xml as the test case (as you suggested).

I'll start out simple sending a 'something' command and waiting for a reply. Will ask you if PLUS acts weird :)

[christiana]

Status so far: COMMAND device is implemented and able to send a message to Plus. When sending a
<Command Name="RequestChannelIds" />
the Plus server responds with an RTS_COMMAND.

So far, so good. Now the reply must be handled in some way, replacing or implementing the QueryNode system in the old OpenIGTLinkIF.