Added

• Introduce reducable demand. It should be listed within sinks, and provided an efficiency (number between 0 and 1). This efficiency correspond to the percent of the demand which must be provided (critical demand). The oemof-solph sinks which models the non-critical part of the demand has very small variable_costs such that it should not influence the costs calculations but should be fulfilled rather than dumping energy into excess sinks. Developed for the server version. (#969)
• Possibility to set min and or max for the load of a transformer and solve for a non-convex optimization. The simulation time can be quite long with cbc solver! Developed for the server version. (#969)

Changed

• Add costs to excess sinks of busses. If the dictionary containing the information about the bus contains a key "price", its value will be applied to the variable costs of the sink (unit of the price is currency/energy unit, default currency/kWh). Developed for the server version. (#969)

• black version was bumped to 24.3.0 (#971)