windfarmGA 4.0.0

• Depends on R 4.1.0
• Removed package dependencies rgdal and rgeos
• Replaced dependency raster with terra
• Moved dependencies foreach, parallel, doParallel, elevatr to Suggests
• 3D-circle intersection calculation. Especially relevant if the terrain model is activated.
• Fix grid_area and hexa_area functions for sf-1.0 and s2
• Removed most visibility functions in favor of terra::viewshed
• Removed the function windfarmGA, as it was redundant and just difficult to test.
• Changed most cat() and print() calls with message()
• Reset old par settings