Clean up for example scripts and macro_params.py, pass macro data date ranges,

[jdebacker]

This PR makes the following enhancements:

1. Clean up of the run scripts (all output files, including plots and CSV file, saved to a common directory, style file imported from package, more in line comments)
2. Include two new kwargs in the Calibrate class object which represent the date ranges for macro data. Update the get_macro_params function to take these arguments.
3. Clean up of calibrate.py: take out references to estimating $\chi^n$ and tax functions, neither of which are used due limited data (at the moment)
4. Reorganize macro_params.py to better organized calls to different data sources
5. As a work around for the World Bank WDI API not responding 100% of the time, create try/except workaround.

[codecov]

Codecov Report

Attention: Patch coverage is 78.94737% with 8 lines in your changes missing coverage. Please review.

Project coverage is 56.40%. Comparing base (516df70) to head (fce9545).

Files	Patch %	Lines
ogzaf/macro_params.py	87.50%	3 Missing ⚠️
ogzaf/utils.py	62.50%	3 Missing ⚠️
ogzaf/calibrate.py	50.00%	1 Missing ⚠️
ogzaf/input_output.py	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #71      +/-   ##
==========================================
+ Coverage   55.07%   56.40%   +1.33%     
==========================================
  Files          12       12              
  Lines         345      367      +22     
==========================================
+ Hits          190      207      +17     
- Misses        155      160       +5     

Flag	Coverage Δ
unittests	56.40% <78.94%> (+1.33%)	⬆️

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[rickecon]

@jdebacker. This looks great. Thanks for this. Merging as soon as tests pass.