Refactor losses modules

[ArdtK]

Current situation Module losses is called for both analyses SINGLE_LINK_LOSSES and MULTI_LINK_LOSSES (analysis_factory.py). From the execute the module single_link_redundancy or multi_link_redundancy is called, based on the value of analysis.

Potential improvements

• Call single_link_losses and multi_link_losses instead of single_link_redundancy and multi_link_redundancy. Convert losses into a common losses module (without execute) to contain the common functionality for both types op losses analyses.
• Merge single_link_redundancy and multi_link_redundancy if the overlap is huge.

Question: what is the function of modules single_link_losses and multi_link_losses atm? They don't seem to be called atm.

[ArdtK]

Discuss with @sahand-asgarpour and @Carsopre

[ArdtK]

After discusion with @Carsopre it is chosen to convert Losses into an abstract base class LossesBase, from which single_link_losses and multi_link_losses inherit.