Water Treatment doesn't give option to add salts "freehand"

[DougEdey]

Converted from SourceForge issue 3015606, submitted by dlevey

It seems that the Water Treatment tab will calculate salts based upon pre-determined water profiles. However, it doesn't seem to give the opportunity to create new profiles (without hand-modifying the underlying data files) or to simply add pre-measured salts based upon external calculations. v2.0.1