Allow None when setting the state of a PureFluid
Allow None when setting the state of a PureFluid

Allow None as an option when setting the temperature and quality or
pressure and quality of a PureFluid. This mimics similar functionality
for Solutions.

git-svn-id: e76dbe14710aecee1ad27675521492cea2578c83@3213 02a645c2-efd0-11dd-984d-ab748d24aa7e

Cantera/cantera-svn,Cantera/cantera-svn,Cantera/cantera-svn,Cantera/cantera-svn,Cantera/cantera-svn,Cantera/cantera-svn