Add "nodelets" for in-process efficient communications

[jlblancoc]

• Add @jolting 's idea to the new module mrpt-comms.
• Write examples.
• Write unit tests.

[jlblancoc]

This is finally in progress! 👍
Changed the name "node" to "topic" since, I think, it's more accurate...
And created a simple example (subscriber callback not being called yet for some reason, but not looked much to this yet).

[jolting]

I forgot about this one. We have c++17 on now.

[jolting]

I think a filter class might be cool. On construction it subscribes and on destruction it unsubscribes.
Also a method of instantiating filters based on a yaml file.

[jlblancoc]

And we'll end up with a mini ROS2 XDD

I think a filter class might be cool.

👍 yeap!

[jolting]

WIthout being encumbered by interprocess communication. At least initially.

[jlblancoc]

This one was already done time ago: 240f9d4
Closing.