[pr2eus/robot-interface.l, pr2eus/pr2-interface.l] fix: :wait-interpolation returns :interpolatingp on real robot

[furushchev]

NOTICE
This PR changes return value of :wait-interpolation

SUMMARY
the return value of :wait-interpolation is defined in docs as below:

return values is a list of interpolatingp for all controllers, so (null (some #'identity (send ri :wait-interpolation))) -> t if all interpolation has stopped

but on real robot it returns (send-all controller-actions :wait-for-result))
So I fixed according with docs.

tested on pr2-simulator and pr1012 real robot.

discussed at #187

[furushchev]

@k-okada @snozawa How do you think of it?

[snozawa]

I think we also need to discuss the return value of :interpolatingp.

According this discussion,
#187 (comment)
#187 (comment)
do we need to return nil when interpolation is finished and some error occurs.

Questions:

• Should return values of :wait-interpolation and :interpolatingp be same?
• :interpolationgp returns t if interpolation finished normally, otherwise returns nil (not finished or finished under some errors). Is this correct?

[snozawa]

For minor comments, it would be better to add more information for this like
wait-interpolation debug: start of robot-interface's :wait-interpolation

[furushchev]

@snozawa Thank you for revieweing.

• Should return values of :wait-interpolation and :interpolatingp be same?

No,

• robot-interface and action-controller instances both have each :interpolatingp method
• :interpolatingp of robot-interface returns t only when all controllers are not interpolating, otherwise returns nil.
• :wait-interpolation of robot-interface returns list of results of all controllers' :interpolatingp.

so when robot stops,

:wait-interpolation => (nil nil nil nil)
:interpolating => nil

• :interpolationgp returns t if interpolation finished normally, otherwise returns nil (not finished or finished under some errors). Is this correct?

I think it returns t only when finished any motion.
When "finished under some errors", it should return nil.

[snozawa]

Thanks, I see.
LGTM.