Issue with initializing previously-initialized simulation #14
Description
If you run init_sim_NComponent on a simulation which already was initialized, it will not remove the fields already added. For a two component NComponent sim, there are 4 phases, so running init_sim_NComponent twice on a simulation instance will result in there being 8 fields. This will trick the engine into thinking the simulation is of a 6-component simulation, and will fail when the TDB does not have 6-components to retrieve data for.