[!104] issue related to gauss-lobatto quadrature rule generated from maxima script

Merge branch 'issue/maxima_script' into 'master'

### Summary

Resolves a bug in gausslobatto.mac script where coefficients are generated
only with double precision instead of high-precision.

Closes [#18]

See merge request [!104]

  [#18]: gitlab.dune-project.org/core/dune-geometry/issues/18
  [!104]: gitlab.dune-project.org/core/dune-geometry/merge_requests/104


Closes #18

dune/geometry/quadraturerules/gausslobatto.mac

@@ -18,7 +18,7 @@ maxp: 30$
 
 /* points are given as the roots of (x^2-1)*L_p(x) */
 point(n) := (x^2-1)*diff(legendre_p(n,x),x)$
-weight(n,xx) := ratsimp(2/((n*(n+1))*legendre_p(n,xx)^2))$
+weight(n,xx) := at(ratsimp(2/((n*(n+1))*legendre_p(n,x)^2)), x=xx)$
 
 /*
   write files