Add isEchelonForm and isReducedEchelonForm

[Goneiross]

No description provided.

[codecov]

Codecov Report

Merging #84 into master will increase coverage by 0.61%.
The diff coverage is 95.12%.

@@            Coverage Diff             @@
##           master      #84      +/-   ##
==========================================
+ Coverage   61.32%   61.94%   +0.61%     
==========================================
  Files          25       25              
  Lines        2211     2252      +41     
  Branches      271      280       +9     
==========================================
+ Hits         1356     1395      +39     
- Misses        777      779       +2     
  Partials       78       78

Impacted Files	Coverage Δ
src/abstractMatrix.js	63.66% <95.12%> (+1.62%)	⬆️

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[lpatiny]

@targos It is an important property of a matrix. Is this ok to merge in the project ?

[targos]

Thank you @Goneiross !