Ep/ensemble calc

[jnsLs]

replaced ethanol model: - old model was not compatible with CastTo64 transform anymore - new model is trained on rmd17 instead of md17

now implemented: SpkCalculator SpkEnsembleCalculator <- inherits from SpkCalculator BatchwiseCalculator <- inherits from SpkCalculator BatchwiseEnsembleCalculator <- inherits from SpkEnsembleCalculator SimpleEnsembleAverage (example for a particular average strategy)

the calculators have two new methods (to allow for more modular classes): _collect_results <-- calculates model outputs and converts property units _ase_specific_output_format <-- for individual structures this converts energy output to scalar value, for batches of structures it keeps the output in array form

updated batchwise optimization howto jupyter notebook --> 01_howto_batchwise_relaxations.ipynb

added howto_ensemble_calculations jupyter notebook --> 02_howto_ensemble_calculator