Remove event based logging pattern

[adrianmolzon]

Hey all, I'm back with another pull request! This one removes some of the old functionality for saving logs since I've created a better way of saving state. In doing so, I've tried to simplify the file structure, mostly by deleting unnecessary files, but also by moving all the logging methods to a Logger class in logger.py. This class is now invoked on initialization of the BayesianOptimization object, and exposes the steps previously invoked by the Observable pattern, optimization_start, optimization_step, and optimization_end. I think this unification is cleaner. Changes to the format of the Logger can still be made, they are just stored under optimizer.logger.whateveryouwant.

[codecov]

Codecov Report

Attention: Patch coverage is 98.61111% with 1 line in your changes missing coverage. Please review.

Project coverage is 97.92%. Comparing base (626aafe) to head (6edcb2a).

Files with missing lines	Patch %	Lines
bayes_opt/logger.py	98.41%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #557      +/-   ##
==========================================
+ Coverage   96.43%   97.92%   +1.49%     
==========================================
  Files          12       10       -2     
  Lines        1235     1158      -77     
==========================================
- Hits         1191     1134      -57     
+ Misses         44       24      -20     

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[till-m]

I think it's generally great that we're moving on from the observer pattern, however, I think it would be better to not pass in the whole BayesianOptimization object in these steps, but pass the specific relevant information. E.g., in log_optimization_step, we should pass in the params of the point, the target value, constraint-value, if applicable, and a boolean for is_new_max. Similarly, the log_optimization_start function should accept parameter names, etc.

The only argument that I can see against this is if we want to allow people to write their own loggers, but I don't really see a usecase for this.

[till-m]

@adrianmolzon if you feel like losing your sanity you could also have a look at tackling #515.

[adrianmolzon]

@adrianmolzon if you feel like losing your sanity you could also have a look at tackling #515.

Cute, I'll see if I can fix this. Looks like a good time to knock this out

[adrianmolzon]

@adrianmolzon if you feel like losing your sanity you could also have a look at tackling #515.

Yeah this sucked but I've made some changes to fix this. To make things easier, any number over a million will be converted into scientific notation, hope this doesn't ruin anybody's day.