Merge pull request #108 from inducer/dt_utils

doc/index.rst

doc/misc.rst

doc/references.rst

doc/utils.rst

examples/advection/surface.py

examples/advection/var-velocity.py

examples/advection/weak.py

examples/maxwell/cavities.py

examples/wave/var-propagation-speed.py

examples/wave/wave-min-mpi.py

examples/wave/wave-min.py

examples/wave/wave-op-mpi.py

examples/wave/wave-op-var-velocity.py

examples/wave/wave-op.py

grudge/dt_finding.py

grudge/dt_utils.py

grudge/models/__init__.py

grudge/models/advection.py

grudge/models/em.py

grudge/models/wave.py