Reduced number of parameters used to define building classes and general new-ESRM20 update

See merge request !22

Fixed bug in get_area_polygon_on_Earth()

Closes #12

See merge request !21

Adjust occupancy sub-types classification and narrow down commercial building classes based on occupancy type

See merge request !19

Adaptation of the GDE prototype code to work with quadtiles instead of 10-arcsec cells

See merge request !18

Created alternative function to retrieve GHS built-up area from OBM
Tiles database in GDE_TOOLS_psql.py (connection to the database opened
before calling the function). Updated config file template and reader
accordingly.