WIP: Symmetric ordering

[david-pl]

I implemented a simple struct that acts as a QSym avoiding application of commutation relations. This can be used in a simple method for computing the symmetrized equations out of the set of equations that uses normal ordering. As a first test I generalized the example using position and momentum operators from the documentation to higher orders (https://qojulia.github.io/QuantumCumulants.jl/dev/implementation/#interface).

[codecov[bot]]

Codecov Report

Merging #36 (9debb31) into master (7b0c103) will increase coverage by 0.31%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #36      +/-   ##
==========================================
+ Coverage   82.76%   83.08%   +0.31%     
==========================================
  Files          15       16       +1     
  Lines        1700     1726      +26     
==========================================
+ Hits         1407     1434      +27     
+ Misses        293      292       -1     

Impacted Files	Coverage Δ
src/printing.jl	49.09% <100.00%> (+3.99%)	:arrow_up:
src/symmetrize.jl	100.00% <100.00%> (ø)
src/utils.jl	95.97% <0.00%> (+0.57%)	:arrow_up:

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 7b0c103...9debb31. Read the comment docs.