Investigate about the possibility of storing some configuration data

[S-Dafarra]

Right now we need to add channels, and then data is store with the corresponding time instant.

Sometimes, it is useful to store also some configuration data, like the list of joints or the version of the software used.

One hack could be add a channel, and then save only one data point, but this is a bit inefficient.

cc @AlexAntn @Nicogene @traversaro @GiulioRomualdi

[S-Dafarra]

Possibly related https://github.com/ami-iit/matio-cpp/issues/53