BUG: "faSchemes" files misleadingly include the "snGradSchemes" entry

When a finite-area case could not find an entry for "lnGradSchemes" in the "faSchemes" file, the "corrected" scheme has been picked up by default. Therefore, any changes in "snGradSchemes" entry will not be read by finite-area models.

However, the standard tutorials misleadingly include "faSchemes" files with the "snGradSchemes" entry instead of the "lnGradSchemes".