Use "nodefaults" in CI conda env file

See merge request !79

Add check if a MeshElementGroup is affine

See merge request !76

Fix curve closedness check in make_curve_mesh

See merge request !78

Boundary tag bit safer

See merge request !77

* check all elements, not just the first one
* check all second derivatives (including cross ones)
* add tests for all of that

Fix some links and typos in the docs

See merge request inducer/meshmode!75

Add CI job to test examples on Github

Test examples during CI

See merge request inducer/meshmode!74

Add cartoon DG solver

See merge request inducer/meshmode!70