Modify libYARP_robotinterface and yarprobotinterface to support passing using ${portprefix} in parameters

[traversaro]

Fix half of #2492 by actually making use of the portprefix attribute.

For example, this can be used as in the following example XML example:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE robot PUBLIC "-//YARP//DTD yarprobotinterface 3.0//EN" "http://www.yarp.it/DTD/yarprobotinterfaceV3.0.dtd">

<robot name="robotinterfaceExample" portprefix="/icub" build="0" xmlns:xi="http://www.w3.org/2001/XInclude">
    <devices>
        <device name="fake_motor_device" type="fakeMotionControl">
        	<group name="GENERAL">
                <!-- Number of joints of the fake_motor_device -->
		        <param name="Joints">            3         </param>
	        </group>
        </device>
        <device name="fake_motor_nws_yarp" type="controlBoard_nws_yarp">
            <!-- See https://www.yarp.it/latest/classControlBoard__nws__yarp.html for parameter documentation -->
            <param name="name"> ${portprefix}/body </param>
            <param name="period"> 0.01 </param>
            <action phase="startup" level="5" type="attach">
                <!-- This is the same name that we specified with the name attribute of the device element of a previously created device -->
                <param name="device"> fake_motor_device </param>
            </action>
            <action phase="shutdown" level="5" type="detach" />
        </device>
    </devices>
</robot>

if this xml is put in file is called config.xml, then it would be possible to call:

yarprobotinterface --config config.xml

and the YARP ports /icub/body/stateExt:o will be created. If one calls instead:

yarprobotinterface --portprefix /icub02 --config config.xml

the YARP ports /icub02/body/stateExt:o will be created

Help robotology/icub-models-generator#215 by providing a way in which two identical models can be spawned in a simulation while changing only the ${portprefix}.

Note: until now the portprefix was used without initial / (see for example https://github.com/robotology/robots-configuration/blob/f3fef4277717ae87d825a9a46d994ccd21fef3ec/experimentalSetups/torsoSkinLaptop/torsoSkinLaptop.xml#L2). However, it seems to be more in line with the rest of the devices to be explicit and indicate the initial /. In any case, the existing configuration files would need to be modified to use the ${portprefix} attribute, so it should not be a big problem to add the / to the portprefix.

Progress:

• Implementation ✅
• Tests ✅
• Documentation ✅ (I had also to add a first skeleton of docs on yarprobotinterface otherwise I would not know where to document the ${portprefix}option

[update-docs]

Thanks for opening this pull request! The maintainers of this repository would appreciate it if you would update the release notes by adding a file in doc/release/<target_branch>, based on your changes.

[traversaro]

The test failures seems unrelated, so I think that the PR is ready for review.
FYI @Nicogene @lrapetti @ste93 @randaz81

[ste93]

it seems that it has been killed, I've tried to re-run the first to see if it changes

[ste93]

Shouldn't this be on master @elandini84 @randaz81? (yarp 3.7)

Suggested change

	robotinterface_portprefix {#yarp_3_6}
	robotinterface_portprefix {#yarp_3_7}

[traversaro]

We can have it on yarp 3.7 (master), but I guess this will delay gazebo-yarp-plugins 5 release (see robotology/gazebo-yarp-plugins#594) until YARP 3.7 is released.

[ste93]

for me can be also merged in 3.6, @randaz81 @elandini84 do you agree?

[elandini84]

Since the new feature is actually fixing part of a reported issue (#2492) and it doesn't affect the already existing code or xml files, for me it can be merged on yarp-3.6.

[ste93]

btw for me it is ok to merge

[traversaro]

As agreed with @randaz81 face to face, we moved this PR to target master as no further release will be done on the yarp-3.6 so there is no point in getting this change in yarp-3.6.

[randaz81]

/rebase