dg1d: Add Bsplines1

Continuation of !210 (merged)

This adds a dispatch type Bspline1 similar to Bspline2. Based on this we implement the necessary method to be able to use it in DGElement.

I also fixed a subtle bug in the quadrature rules I used in some of the Bspline methods. That is, I accidentally used a LG rule with Npts=2, which corresponds to a N=Npts-1=1 order rule that is exact for polynomials up to 2*N=2 order. But for Bspline2 we encounter fourth order polynomials, so we should be using Npts=3.

Also adds a new option to the Mesh parameters section:

• kind = "modal_bspline1": Utilize a 1st order modal Bspline Ansatz for the DG evolution.

added feature mesh parameters refactor tests labels

added 1 commit

• 15a822df - update bspline plot script

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The abstraction for the Bspline module could be improved. Atm one has to remember that bs1 = Bspline1(z), bs2 = Bspline2(z) and bs1.Npts == bs2.Npts, but we would use bs1.Npts and bs2.Npts+1 DOFs for a DG evolution, respectively.

enabled an automatic merge when the pipeline for 15a822df succeeds

aborted the automatic merge because source branch was updated

added 1 commit

• 0ae37f86 - update reftest modal_bspline2_advection_sine

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enabled an automatic merge when the pipeline for 0ae37f86 succeeds

merged

mentioned in commit cb7c756e