[ENH] Suggestion: Alternative parameter name for format argument in _to_datetime method

[genedan]

In the TriangleBase class there is a method called _to_datetime that has an argument called format:

@staticmethod
def _to_datetime(data, fields, period_end=False, format=None):

I'm getting a warning from my IDE that format shadows a built-in name in Python. I propose that we rename it to something else, maybe datetime_format.