Fix models

[harrahx3]

• Fixing several inconsistencies in the models names, parameters, docstrings, documentations. Change the name of some models (remove 'SenergyNets').
• Adding constraints on boilers and heat pump models: minimum running power, maximum ramping up/down speeds + tutorial and tests.
• Ensure the mass flow distributed by the boilers and heat pump is equal to the mass flow received by the receiver.s after merit order capping.