Coda transformations - Add selection of columns/attributes of the input data

[nmaarnio]

Relates to EIS QGIS Plugin issue GispoCoding/eis_qgis_plugin#244

ALR, Inverse ALR, CLR, Inverse CLR, Single ILR, Single PLR, Pivot logratio should have option to select columns/attributes of input data as targets for the transform

@em-t @jtlait I'll look into this and GispoCoding/eis_qgis_plugin#244

[jtlait]

@msorvoja Ok good to hear, I will soon complete the issue 448