new SBP coefficients of Diener, Dorband, Schnetter, Tiglio (2007)

[ranocha]

Closes #128. This includes the diagonal-norm operators of

@article{diener2007optimized,
  title={Optimized high-order derivative and dissipation operators satisfying
         summation by parts, and applications in three-dimensional multi-block
         evolutions},
  author={Diener, Peter and Dorband, Ernst Nils and Schnetter, Erik and
          Tiglio, Manuel},
  journal={Journal of Scientific Computing},
  volume={32},
  number={1},
  pages={109--145},
  year={2007},
  publisher={Springer},
  doi={10.1007/s10915-006-9123-7}
}

The corresponding dissipation operators follow the recipe of Mattsson, Svärd, Nordström (2004), so they are available via dissipation_operator (up to the scaling epsilon vs. epsilon / 2^accuracy_order).

[codecov]

Codecov Report

Merging #129 (1de347d) into main (21d463f) will decrease coverage by 1.88%.
The diff coverage is 32.25%.

@@            Coverage Diff             @@
##             main     #129      +/-   ##
==========================================
- Coverage   91.94%   90.05%   -1.89%     
==========================================
  Files          30       31       +1     
  Lines        4741     4896     +155     
==========================================
+ Hits         4359     4409      +50     
- Misses        382      487     +105     

Flag	Coverage Δ
unittests	90.05% <32.25%> (-1.89%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/SummationByPartsOperators.jl	100.00% <ø> (ø)
...P_coefficients/DienerDorbandSchnetterTiglio2007.jl	32.25% <32.25%> (ø)

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[coveralls]

Coverage decreased (-1.9%) to 90.053% when pulling 1de347d on hr/DienerDorbandSchnetterTiglio2007 into 21d463f on main.

[ranocha]

CC @eschnett