Remote control board: remove single port compatibility

[barbalberto]

This PR remove the backward compatibility of the remote control board with wrapper that has ONLY the state:o port.

This device is therefore expecting the wrapper to have the stateExt:o port, which was introduced in 30/07/2014.

[traversaro]

typo: connectin --> connecting

[traversaro]

I can't withdraw my review, but there is an important point that I think we already discussed some time ago but I forgot about the outcome of that discussion.
This PR (by changing the protocol number) will break the YARP-level compatibility between master and devel (even if, bypassing the protocol check) everything will be working fine.
As the protocol on the stateExt:o did not change, perhaps we can think about avoiding this unnecessary incompatibility?

[barbalberto]

I changed the protocol number to have a clear error message.
Without it, if a user tries to connect a remotecontrolboard after this change to a controlboardwrapper that only has state:o port, he/she will get a connection error whitout knowing why or what to do about it.
I think this PR does change the protocol, in the sense that some data was going through a port, and now goes though a different port (if you see from the perspective of a CBW with only state:o to a CBW with the stateExt:o)
It works if both client/server are updated enough, it will not work anymore if thay are old (pre compatibility hack was introduced). Since this hack it is what I'm removing, for them it is a change of protocol.

Anyway the next change I'm working on will change the protocol for sure since I'm gonna change the data structure of stateExt :-P

For sure it is annoying to break master / devel compatibility.
I don't see any other way, but I'm open to suggestions

[traversaro]

I see, then I agree that a protocol version change is inevitable, especially if you plan to change it again in a short time.. Can we wait at least tomorrow for merging this? : (

[barbalberto]

Yes, no rush in merging it

[drdanz]

Please add a line or two (for this PR, but in general for any PR on yarp) in the relative release notes file (in this case doc/release/v2_3_70.md)

[traversaro]

I documented the necessary steps to use devel with the superbuild in https://github.com/robotology/codyco-superbuild#handling-the-devel-branch , for what it concerns that problem the PR can be merged.

[barbalberto]

Updated doc and fixed typo in error message.
Can we merge?

[drdanz]

31/12/2016 30/07/2014? Just forget about the dates next time, nobody cares... 😆

[drdanz]

Merged, thanks!