Add check for algebraic stability

[ranocha]

No description provided.

[coveralls]

Coverage increased (+0.02%) to 79.659% when pulling 401b513 on ranocha:stability_checks into 640ec1b on ketch:master.

[coveralls]

Coverage increased (+0.02%) to 79.659% when pulling 401b513 on ranocha:stability_checks into 640ec1b on ketch:master.

[codecov-io]

Codecov Report

Merging #56 into master will increase coverage by 0.01%.
The diff coverage is 88.88%.

@@            Coverage Diff             @@
##           master      #56      +/-   ##
==========================================
+ Coverage   79.64%   79.65%   +0.01%     
==========================================
  Files          21       21              
  Lines        4455     4464       +9     
==========================================
+ Hits         3548     3556       +8     
- Misses        907      908       +1

Impacted Files	Coverage Δ
nodepy/runge_kutta_method.py	86.89% <88.88%> (+0.01%)	⬆️

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