uniform running modes

[mgiulini]

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Closes #756 and Closes #784 by:

• retrieving the correct engine for each (intensive) analysis module.
• substituting "hpc" with "batch" everywhere in the repo
• adding a function in the analysis modules such that the analysis is run in local mode when selecting the "batch" mode
• modifying the default number of cores from 8 to 4 so as to not overload the login/local nodes