ENH: riemann_compare module

New module for comparing various implementations of Riemann solvers.
added riemann shootout framework
iso_c variant
fixes #248 (riemann_compare branch)
f2py-based compile flags in Makefile
added 2D shallow water test
don't propagate failed import
revert whitespace, 1D/2D/3D claw_packge init fixes
added vis ability
Remove duplicate code in petclaw state object.
Merge pull request #281 from ketch/rm_duplicate_code

Remove duplicate code in petclaw state object.
Stop swallowing error in IO test.
Fix petclaw convenience plotting.
Merge pull request #284 from ketch/fix_plotting

Fix petclaw convenience plotting.
Merge pull request #283 from ketch/test_fails_appropriately

Stop swallowing error in IO test.
Merge branch 'master' into riemann_shootout

* master:
  Fix petclaw convenience plotting.
  Stop swallowing error in IO test.
  Remove duplicate code in petclaw state object.
  Print missing file errors to stdout.
  Update gitignore files.
  Working gallery.
  Add missing import.
  More work on gallery.
  Partially working gallery construction.
  Stuff.
  Use .rst for the gallery.
  Several small improvements in ascii.py.
  Make quick Domain setup use distinct Dimension names.
  Add quadrants example (2D Euler).
  Update README and docs.
  More informative error messages.
  Eliminate repetitive property code by overriding __getattr__.
Make apps return controller.
Fix directory in 3d acoustics test.
Fix up doc strings, simplify some functions, etc.
Merge pull request #288 from ketch/general_maintenance

Fix up doc strings, simplify some functions, etc.