fix(gridgen): trap duplicate vertices #1492

[wpbonelli]

• remove near-duplicate vertices produced by GRIDGEN, with tunable precision
• fix DISV model produced by gridgen not converging when original delr/delc contain decimals #1492

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.1%. Comparing base (029a4e1) to head (e62ae32).
Report is 7 commits behind head on develop.

❗ Current head e62ae32 differs from pull request most recent head 79d9bb0. Consider uploading reports for the commit 79d9bb0 to get more accurate results

Additional details and impacted files

@@            Coverage Diff            @@
##           develop   #2119     +/-   ##
=========================================
+ Coverage     68.3%   73.1%   +4.8%     
=========================================
  Files          260     259      -1     
  Lines        57947   59448   +1501     
=========================================
+ Hits         39611   43503   +3892     
+ Misses       18336   15945   -2391     

see 197 files with indirect coverage changes

[langevin-usgs]

Thanks for looking at this, @wpbonelli.