Module Hydrograph Improvements
(1) in module “hydrograph” changed WLmax name for WLmin everywhere because it was more adequate.
(2) Implemented the option in the module “hydrograph” to plot water level as mbgs or masl. The option is controlled by the GraphParameters class variable “WLref”. The option has not been linked with the UI yet.
(3) Improved the method “best_fit_waterlvl” in the class “GraphParameters”