Merge pull request #39 from rjleveque/rjl

Mostly improve regression tests.  And close some data files after writing
Merge pull request #40 from rjleveque/rjl

fixed make_clawtop.sh
Merge pull request #41 from rjleveque/rjl

Added relocatable parameter to compare_regression_tests, so image files ...
Merge remote-tracking branch 'upstream/master' into rjl

* upstream/master: