Impl stats lin sol write json

[cpmech]

No description provided.

[codecov-commenter]

Codecov Report

Merging #68 (8fe50b5) into main (048e20d) will decrease coverage by 0.01%.
Report is 2 commits behind head on main.
The diff coverage is 98.07%.

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@@            Coverage Diff             @@
##             main      #68      +/-   ##
==========================================
- Coverage   98.41%   98.41%   -0.01%     
==========================================
  Files         101      101              
  Lines       20562    20605      +43     
==========================================
+ Hits        20237    20279      +42     
- Misses        325      326       +1     

Files	Coverage Δ
russell_lab/src/base/sort.rs	100.00% <ø> (ø)
russell_sparse/src/stats_lin_sol.rs	98.50% <98.07%> (-0.23%)	⬇️

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