List and describe meta keywords for sps

While I was developing new sps pannel, I realized that's the keywords we have now are too specific to describe the whole spectrograph system.

It won't be a good choice to put that logic directly in the GUI.
Moreover, actors are good as such things, so we'll use a spsActor to update these new meta-keywords. As they'll be stored in the database, they will be also accessible from a web page.

fmadec and I will carefully list the missing keywords that we think of.
In this meta-keyword list, we will describe also on which existing keywords they depend and what's the logic.

Then, the design of the GUI will be quite straight-forward and evolve according to this list.