changed some of the initialization logic. Now, the DaCycle object has become internal to the obsoperator, sample, and statevector objects

DaSystem
DaPlatform
ObservationOperator

are now handled before the pipeline, from the das.py contents. This replaces the situation in which they were all 
constructed inside the pipeline based on rc-file items from the da.rc script. This now only serves to identify the 
cycle information, and no longer hold info about the platform, sampling model, and da system used inside a cycle.