Don't use PWD environment variable when setting path to input files. Closes #302 on github.
Don't use PWD environment variable when setting path to input files. Closes #302
on github.

smharper/openmc,smharper/openmc,walshjon/openmc,paulromano/openmc,smharper/openmc,samuelshaner/openmc,lilulu/openmc,shenqicang/openmc,samuelshaner/openmc,sxds/opemmc,shenqicang/openmc,amandalund/openmc,sxds/opemmc,wbinventor/openmc,mit-crpg/openmc,mit-crpg/openmc,liangjg/openmc,amandalund/openmc,johnnyliu27/openmc,mjlong/openmc,wbinventor/openmc,bhermanmit/openmc,johnnyliu27/openmc,nhorelik/openmc,lilulu/openmc,samuelshaner/openmc,kellyrowland/openmc,johnnyliu27/openmc,kellyrowland/openmc,bhermanmit/openmc,johnnyliu27/openmc,walshjon/openmc,samuelshaner/openmc,wbinventor/openmc,paulromano/openmc,liangjg/openmc,shikhar413/openmc,wbinventor/openmc,shikhar413/openmc,mjlong/openmc,liangjg/openmc,mit-crpg/openmc,shikhar413/openmc,amandalund/openmc,lilulu/openmc,smharper/openmc,nhorelik/openmc,walshjon/openmc,amandalund/openmc,walshjon/openmc,paulromano/openmc,liangjg/openmc,paulromano/openmc,shikhar413/openmc,mit-crpg/openmc