Adds option called get_event_counts to CatalogForecast and adds arguments to plotting functions

[wsavran]

added verbose option to catalog based tests
added get_event_counts method to CatalogForecast
added plotting arguments for more granular customization

pyCSEP Pull Request Checklist

Please check out the contributing guidelines for some tips
on making pull requests to pyCSEP.

Type of change:

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[codecov-commenter]

Codecov Report

Merging #146 (cd39f61) into master (aa078b3) will decrease coverage by 0.34%.
The diff coverage is 25.58%.

@@            Coverage Diff             @@
##           master     #146      +/-   ##
==========================================
- Coverage   56.82%   56.48%   -0.35%     
==========================================
  Files          19       19              
  Lines        3201     3233      +32     
  Branches      469      479      +10     
==========================================
+ Hits         1819     1826       +7     
- Misses       1264     1288      +24     
- Partials      118      119       +1     

Impacted Files	Coverage Δ
csep/core/catalog_evaluations.py	7.94% <13.88%> (-0.79%)	⬇️
csep/core/forecasts.py	55.19% <85.71%> (+0.78%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update aa078b3...cd39f61. Read the comment docs.