Log and make calculations reproducible

[aleksandra-kim]

Original report by Chris Mutel (Bitbucket: cmutel, GitHub: cmutel).

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Logging framework gist here.

Need new input argument for all LCA classes: logpath. This can be either a filepath or a directory (in which case, a log filename is generated). We then need to log the following:

• Filepaths of all processed arrays for each matrix
• Hash of each processed array. This is fast, ~one millionth of a second per array.
• Functional unit
• Seed value for RNGs if Monte Carlo

Brightway2-data will be updated to include a new datastore for these logfiles, and utility functions to read the logs and construct the necessary arguments to reproduce the calculations.

[aleksandra-kim]

Original comment by Chris Mutel (Bitbucket: cmutel, GitHub: cmutel).

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Need to generate a random seed ourselves if it isn't explicit. Should be a 32 bit unsigned integer.