added calculate_svi action
added loop for calculate_svi
initial svi calculation
Fixed calculations
Improve add attributes to layer
Merge branch 'improve-add-attributes-to-layer' of github.com:gem/qt-experiments into apply-weights
Fix adding attributes
Merge branch 'improve-add-attributes-to-layer' of github.com:gem/qt-experiments into apply-weights
use add_attributes key
refnaming calculate_svi to calculate_iri
copleted renaming in UI files
added gui for calculate IRI
added gui logit to add aal layer and attribute selection for IRI calculation
added guards for raster layers.
added methods to fill a a combo with layers.
added docs
added TODO
Fix find_attribute_id; add tests to ProcessLayer for methods find_attribute_id and add_attributes and move also previous tests into test directory
Test for transformations have been moved to the test directory
Avoid using find_attribute_id in add_attributes, because we don't need the id