Generalize blockisequal to arrays, introduce blockequals and blockisapprox

[mtfishman]

Generalize blockisequal to arrays, where the definition is that the axes have the same block structure and the array values compare equal with isequal. This PR also introduces blockequals and blockisapprox, which are like blockisequal but use == and isapprox respectively to compare values.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.82%. Comparing base (a4a0b93) to head (9ca5fc0).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #477      +/-   ##
==========================================
+ Coverage   93.81%   93.82%   +0.01%     
==========================================
  Files          19       19              
  Lines        1761     1764       +3     
==========================================
+ Hits         1652     1655       +3     
  Misses        109      109              

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