Corrected error in HumidifierPrescribed and improved variable names and documentation.

This is for #33.
Merge branch 'master' into issue33_humidifier2

Conflicts:
	Annex60/Resources/ReferenceResults/Dymola/Annex60_Fluid_MixingVolumes_Examples_MixingVolumeMoistAir.txt
Merge pull request #48 from iea-annex60/issue33_humidifier2

Issue33 humidifier2