Fix bug when using <nuclides>all</nuclides> with a void material present.
Added new test in test suite to check for <nuclides>all</nuclides> with void
material.
Merge branch 'develop' into fix-all-nuclides-void
Fixed tallying for specific <nuclides> in a void material. The earlier change
only fixed the special case of <nuclides>all</nuclide>.
Updated test_tally_nuclides to include a tally containing a <nuclide> filter
with only one nuclide.
Merge branch 'develop' into fix-all-nuclides-void
Added try/finally in test_tally_nuclides.py.
Merge branch 'develop' into fix-all-nuclides-void
Merge pull request #280 from mit-crpg/fix-all-nuclides-void

Fix tallying <nuclides> with void materials
Change command-line help flag to -h.
added examples for other nuclear data libraries, changed all to 300 K
Fix typo in user's manual for 'separate' attribute of source_point.
delete example inputs for all data libraries except those from nndc
Changed fox URL to a public URL
Merge pull request #283 from walshjon/other-library-examples

added examples for other nuclear data libraries, changed all to 300 K
Merge pull request #284 from smharper/fox_public_URL

Changed fox URL to a public URL