Further improvements to field mapping

[Jdgilby]

The recent release addressed issue #552, however this only address categorical fields, not numerical. There isnt currently a good pathway/workflow to deal with numerical fields which often have a bunch of different values. Batch edit wouldn't make sense for unique values, field mapping doesnt work, and manual edits through the form would be too time consuming.

I'm suggesting the possibility to map the attribute itself for numerical values. No value mapping is needed for the numerical data. So Under the field mapper Id want to specify that attribute "length" from the temporary layer = "Length" from the QRIS layer. No need to individual select values.

Currently we get this dialog for this example.

When trying to map I only get categorical fields as an option.

There needs to be the ability to add the field from the temporary layer, and I'm suggesting you don't need to map the actual numbers, they just get copied from one field to the new one.