Negmas

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* More exception resistance in cartesian_tournament
* Base Mechanism class now can ignore exceptions in initialization of agents
* More consistent naming of methods involving negotiators

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* Matching the behavior of Genius in relative_time.
Originally, NegMAS used the following rule for relative_time R:

i = 0 => R = 0

i > 0 => R = min(1, max(t/T, (i+1)/(N+1)))

where i is the current step, t is current time, T is time_limit, N is
n_steps.

After this change the special case at i=0 is removed:

R = min(1, max(t/T, (i+1)/(N+1)))

This matches Genius behavior exactly if we have either T=\infty or
N=\infty.
* More info in printing in cartesian verbose
* Rounding output in cartesian verbose mode
* Printing execution time in cartesian verbose

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* Saving erred-negotiator and erred-agent in MechanismState in case of errors in SAO and related mechanisms
* Saving details about errors (including traceback) in cartesian products (in all_scores.csv).

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* Improving the way some stats are saved in situated
* CLI improvements

Now the "negotiate" CLI has a much better help. Try:

>> negotiate --help

Moreover, we added the ability to generate scenarios and save them as
well as more control over statistics

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* correcting the way some stats are saved. Avoids both double saving of stats in some cases and not saving them at all in others

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* Avoid controller failure if a wrong ID is passed