Implement regularizations for Euler eq

Implements the Navier-Stokes and general regularization from J.-L. Guermond and B. Popov, “Viscous regularization of the euler equations and entropy principles,” SIAM Journal on Applied Mathematics, vol. 74, no. 2, pp. 284–305, 2014.

src/EulerEq/setup.jl

@@ -12,7 +12,8 @@ function Project(env::Environment, mesh::Mesh1d, prms)
   ldg_rsolver, av_rsolver = nothing, nothing
 
   bdrycond = dg1d.DirichletBC2()
-  P = Project(equation, rsolver, hrsc, tci, ldg_rsolver, av_rsolver, bdrycond)
+  fixedprms = (; av_regularization=Symbol(prms["EulerEq"]["av_regularization"]))
+  P = Project(equation, rsolver, hrsc, tci, ldg_rsolver, av_rsolver, bdrycond, fixedprms)
 
   # register variables
   # TODO add a ::Nothing overload for register_variables!