changed default library routines b4step, setaux, qinit, setprob, src from .f to .f90 files, and fixed all Makefiles in tests and examples
changed examples/acoustics_1d_example1 to use .f90 files
changed double precision to real(kind=8)
add regression tests in examples/ to use new code in clawutil
added setplot.py to 3d examples that creates empty _plots directory for now
Merge pull request #59 from rjleveque/default-files-f90

Changed default library files to f90 and added regression tests