Remove another wild 'import *'
An attempt to fix the "make minimal" target to just do the bare minimum cythoning.

Not sure it works.
Fix initialization of coreSpeciesConcentrations in SimpleReactor

Now that y represents mole numbers not concentrations, the initial
setting of coreSpeciesConcentrations needed to be fixed.
Updated conversion calculations in base solver class.

Now that y represents mole number not concentration, we can remove the 
forced assumption of ideal gas law and just calculate conversion directly
from the number of moles.