[GRASS-dev] Major refactoring of r.estimap.recreation

[Nikos Alexandris]

With Panagiotis Mavrogiorgos' invaluable support, `r.estimap.recreation` has been
refactored:

https://gitlab.com/natcapes/r.estimap.recreation/commit/e4547ad5402f3f09d7625f5bfa03cd088cd21768

While there are still pieces to improve and complete (i.e. unit tests),
the whole process is in my humble view a nice collaborative development
example using git(lab).

Skimming through the add-ons, there are still several large monolithic Python
modules.  Please, let us discourage them in the spirit of making GRASS
GIS as a whole easier to work with and develop for, maintain and grow further.

Thank you Pano, Nikos