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• fix bug for stencil sets of linear combination of differential operators
• when generating a stencil set, pass down accuracy in FinDiff definition, not in method call

• Human readable string representation for stencil sets.

Create stencils in any number of dimensions using prescribed set of offset tuples.

Coefficients can now also be calculated from given list of offsets.

Minor bug fixes.

Fixes TypeError issue for high accuracy order.