Address issues in https://github.com/nasa/isaac/pull/103

[marinagmoreira]

          The planner is the component in the architecture that receives a domain and problem instance and returns a plan to execute. A lot of this stuff seems like it is really elsewhere in the achitecture, like it could be part of a `survey_executive` package instead. At the moment, some stuff (like `tmux_inject.py`) that was at a higher level is now being merged into `survey_planner`.

If we are going to stuff everything into one package, probably it should be called survey_manager, since that is the umbrella term for the coordinated execution part of the system of which the planner is one part.

I don't necessarily want to block merge based on issues like this. I just think it fosters confusion when we're talking about the system and different people may have different interpretations of what these words mean.

Originally posted by @trey0 in #103 (comment)