Add Mux and Demux to hydro

[Squelsh]

I was missing a Demux tool. So I brought the old code back to life.
While working on that, I also fixed the service-servers of the Mux tool, so more than one Mux can be used.

Code is tested for hydro. But I think it can also be merged into newer versions. As I have no newer version running, I could not test. ==> Would be nice, if someone could do that.

If my request gets merged, I am happy to update the ROS WIKI page.

[ros-pull-request-builder]

Can one of the admins verify this patch?

[tfoote]

The copyright should be side by side not replace, even though it's mostly new.

Copyright (C) 2009, Morgan Quigley
Copyright (C) 2014, Andreas Hermann

[dirk-thomas]

This comment (https://github.com/Squelsh/ros_comm/blob/hydro-devel/tools/topic_tools/src/mux.cpp#L301) states explicitly that the services are provided on the node "mux" and suggests using remapping in order to use multiple mux instances.

This patch would effectively change the public API of the tool which is not a feasible change for Hydro. Even for Indigo it is questionable if that should be changed.

The demux part is definitely a good additional. Thank you for porting this functionality.

[Squelsh]

Hi Tully, hi Dirk,
sorry for the quirks. I totally agree with your comments.
@tfoote : I corrected the Copyright as suggested.
@dirk-thomas : I reverted my changes and adapted the demux to behave the same way as the Mux.

[dirk-thomas]

I will add the missing install rule (https://github.com/ros/ros_comm/pull/407/files#diff-ae340f410bae427e1853101dfdbade7eR55) when merging it into indigo-devel.

[dirk-thomas]

For mux there are some Python scripts to ease the operations (add, delete, list, select). Wouldn't it make sense to have similar scripts for demux?

[Squelsh]

I did not notice these scripts till now. Will have a look on monday.

[Squelsh]

Wrong button )):

However: I don't see the point in a script, where the copyright is three times the lenghts of the script itself, but I committed the according scripts for the demux.

[dirk-thomas]

Merged to indigo-devel in 4edc26b. It will be backported to hydro-devel before the next patch release. Thank you for the PR.