Squashed 'src/' changes from c876219b..ead498ab

ead498ab Merge pull request #79 from dlparkhurst/mix_error
44093498 fixed error with MIX that Scott found on merge.

git-subtree-dir: src
git-subtree-split: ead498ab60e71b7175c0e4bc6468a0804851ac20

step.cpp

@@ -674,7 +674,7 @@ add_mix(cxxMix *mix_ptr)
 			if (it->second > 0)
 			{
 				intensive = extensive / sum_positive;
-				intensive_water = extensive_water / sum_positive;
+				intensive_water = extensive_water / sum_positive_water;
 			}
 			else
 			{