Remove shapely from dependencies

[anomam]

Since the implementation of vectorized calculations in pvfactors, the shapely dependency has only been in use for plotting PV arrays, so there is really no need for it anymore, especially considering all the trouble it brings because of the GEOS dependency.

The goal of this PR is to remove shapely (and therefore GEOS) as dependency for pvfactors. shapely used to be at the core of the package though, so it will require substantial work to remove it cleanly and clean up the geometry part of the package because of the legacy code.

[renegacitua]

Hi, i'm starting to use pvfactors, is a really great tool, but i had a question. Is the program capable of discretizing the terrain? I mean, I know that it consider the "cut points" and the shadow and not shadow areas, but it can consider a certain zone where I can consider a bigger value of albedo?

In other words, i want to quantify the impact of install a reflective surface on the front or under of the PV row, is this possible with pvfactors? What would you recommend me for this?

I appreciate your help, regards!