Example of using the proposed new constants available from Riemann.
Use new indexing constants in most examples.
Merge branch 'master' into constants_and_indices

* master:
  Add 3D shock bubble example, with IPython notebook plotting example using yt and mplot3d.
  Make sure setplot_func variable always gets defined.
  Don't store gamma1 in problem_data.

Conflicts:
	examples/euler_1d/shocksine.py
	examples/euler_1d/woodward_colella_blast.py
	examples/euler_3d/Sedov.py
	examples/euler_3d/shocktube.py
Merge pull request #454 from ketch/constants_and_indices

Example of using the proposed new constants available from Riemann.