Cleaned up unneeded .f files.  Updated acoustics and stegoton app scripts.
Changed makefiles to use FC instead of just gfortran.
adding src/fortran/2d directory
Wrote 1D interleaved kernels and updated constant advection example
ONLY.  Remaining 1D examples broken.
Branch merge.
Rearranged fortran source directories.
Fixed 1D interleaved kernels.
Added acoustics regression test!
upgraded regression test
trying to maintain more py3 compliance
Made stegoton example work with interleaved kernels.
Renamed classes:
PCGrid -> Grid
PCDimension -> Dimension
Fixed 2D acoustics interleaved example?
Reorganized 2D acoustics directory structure and cleaned up script.
Added data for 2D acoustics regression test.
both examples unit-testing now, please use petscPlot for examples for consistency
Simplified and streamlined the scripts for all the examples.
Each one is now a function.  Lines that just set default parameters
are removed.

Added  petclaw.plot module for automation of simple plotting.

This changeset requires an update of clawpack4petclaw as well.
Resolve some conflicts.
Finished interleaving 2D kernels.
Added work-around for f2py issue with maux=0.
Added dimsp2.pyf interface file.
Updated regression test results to match minor changes (in initial time step)
to test scripts.