Dolphyn - Long-duration storage formulations

This version of Dolphyn was used for the paper \Improved formulation for long-duration storage in capacity expansion models using representative periods\. Different long-duration storage formulations are implemented (Explicit-Hourly, Implicit-Hourly, Implicit-Min-Max - see paper for definitions) and tested on three example systems. Run files are available in the \Example_Systems\ subfolders.