"gnData" parameter "fixState" now acts as a sort of flag that tells which states are necessary to account for in the energy dynamics and with dummy variables. (Avoid formulating unnecessary equations and variables)

NOTE! gnData "fixState" must be input in order to avoid calculating "q_balance" for the node! Even in the case of ts_nodeState "fixState" covering the whole timespan (and thus overwriting dnData "fixState" imposed boundaries) the "q_balance" and "vq_gen" variables are formulated unless a value for dnData "fixState" is provided. This permits fixing node states according to time-series data, and calculating the necessary control resulting in the fixed node state imposed energy dynamics.