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
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.
Remove duplicate Fortran files.
Update riemann_compare.py to work with new Riemann solver names.
Merge branch 'master' into riemann_shootout

* master:
  Fix Riemann solver name in stegoton setplot.py.
  Remove doc directory, as it has been moved to clawpack/doc/doc/pyclaw.
  Fix a few rpn_ that I missed before.
  Update apps to use new Riemann solver module names.
  Fix up doc strings, simplify some functions, etc.

Conflicts:
	apps/advection_1d_variable/variable_coefficient_advection.py
	apps/advection_2d_annulus/advection_annulus.py
Refactor riemann_compare to import apps.
Reorganize riemann shootout directories.
small path fixes
Merge pull request #294 from ketch/riemann_shootout

ISO C solver example and solver_compare.py