quadtree csv reader

[khawajasim]

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[codecov-commenter]

Codecov Report

Merging #186 (a9a35b2) into master (ad217ed) will decrease coverage by 0.10%.
The diff coverage is 50.00%.

❗ Current head a9a35b2 differs from pull request most recent head 876d877. Consider uploading reports for the commit 876d877 to get more accurate results

@@            Coverage Diff             @@
##           master     #186      +/-   ##
==========================================
- Coverage   55.84%   55.73%   -0.11%     
==========================================
  Files          20       20              
  Lines        3560     3572      +12     
  Branches      568      569       +1     
==========================================
+ Hits         1988     1991       +3     
- Misses       1452     1460       +8     
- Partials      120      121       +1     

Impacted Files	Coverage Δ
csep/utils/readers.py	46.98% <22.22%> (-0.86%)	⬇️
csep/core/regions.py	46.75% <77.77%> (+0.02%)	⬆️

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[wsavran]

I think we change this name to quadtree_csv_loader. Reason: this function name implies that it will return a forecast object. Also should change the name of the other function to quadtree_ascii_loader.

[wsavran]

aside from the comment above, this looks good to merge.

[khawajasim]

Can you accept the last two enhancements I added? grid bounds for cartesian gird will be useful for writing generic function for forecast aggregation. And the check for zero cell area is also generally useful. Without this check, the function does not return zero.

[wsavran]

looks good to me ! merging.