Construct OrthoPoly from corresponding measure

[FHoltorf]

In SciML/ModelOrderReduction.jl#27 we would like to construct CanonicalOrthoPolys and generic OrthoPolys from the corresponding Measures. This PR seeks to enable that by defining suitable constructors. Also, it changes the inner constructors to outer to promote extensibility.

Best,
Flemming

[codecov]

Codecov Report

Merging #100 (e6a1b12) into master (2b3d41c) will decrease coverage by 11.95%.
The diff coverage is 97.97%.

@@             Coverage Diff             @@
##           master     #100       +/-   ##
===========================================
- Coverage   90.25%   78.30%   -11.96%     
===========================================
  Files          15       15               
  Lines         965     1005       +40     
===========================================
- Hits          871      787       -84     
- Misses         94      218      +124     

Impacted Files	Coverage Δ
src/typesOrthoPolys.jl	97.82% <97.97%> (-1.14%)	⬇️
src/polynomial_chaos.jl	20.37% <0.00%> (-56.94%)	⬇️
src/show.jl	20.00% <0.00%> (-27.78%)	⬇️
src/recurrence_coefficients_monic.jl	90.47% <0.00%> (-7.15%)	⬇️
src/typesQuad.jl	94.73% <0.00%> (+4.73%)	⬆️

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