Implement Individual Service Calls about isaacs_server HOT 3 CLOSED

Added control_drone service, a generic service that takes in drone ID and a string, and accordingly calls: (the string defines which method to call)

• land_drone
• start_mission
• pause_mission
• resume_mission
• fly_home

We decided to have this generic service because we think it might be cleaner than defining a whole bunch of services that just make 1 function call. These methods don't need any preprocessing, and the only input is the drone ID, so it should be fine.

For things like upload_mission, which need inputs like a list of waypoints, they can have their own service.

from isaacs_server.

Karthik, Varun, and Kyle completed the following:

State dictionaries:

• sensors global dictionary
• drone_names dictionary
• sensor_names dictionary

Service handlers:

• register_sensor

Skeleton code for shutdown_drones

from isaacs_server.

next_id now starts at 1, not 0. 0 is reserved for services to ask for info about ALL drones + services, not a particular one

implemented all_available_drones
implemented query_topics

other minor edits

TODO:
make sensor base class
add list of sensor ids to the parent drone instance when registering a sensor.

from isaacs_server.