Create new addon r.area.createweight (OSGeo#597)

* create r.area.createweight

* remove empty folder

* Add files for new add-on r.area.createweight

This add-on can be used to create a weighting layer for dasymetric mapping using a Random Forest model.

* Update r.area.createweight.py

Correct some formatting errors (Flake8)

* fix Pep8 syntax

* attempt to fix Black formating issue

* Apply suggestions from code review

Co-authored-by: Veronica Andreo <veroandreo@gmail.com>

* Apply suggestions from code review

* Apply suggestions from code review

* Remove njob check as suggested

* Apply Black formating

* fix multi-line option description

* fix 2 issues with multi-line in module description

Co-authored-by: Tais Grippa <tgrippa@ulb.ac.be>
Co-authored-by: Grippa Tais <tais.grippa@ulb.be>
Co-authored-by: Veronica Andreo <veroandreo@gmail.com>

src/raster/r.area.createweight/Makefile.txt

@@ -0,0 +1,7 @@
+MODULE_TOPDIR = ../..
+
+PGM = r.area.createweight
+
+include $(MODULE_TOPDIR)/include/Make/Script.make
+
+default: script