Shading Factor Table Updates

[dtarin]

Hello, 

It would be very useful to see two features related to the shading factor table:

1. Increased resolution in the shading factor table 
   • Allow user to define additional points in the table, or provide additional preset tables with additional values. The purpose of the shading factor table is to reduce simulation time, but it adds additional shading loss. This is fine in principle, but it would be helpful if users could investigate and find that balance between reduced simulation time and reducing the overestimation of shading losses. Additional points in the lower elevations would valuable.  
2. Allow users to manually enter or import shading factor tables, linear and mod. strings
3. Allow shading factor tables to be a variable for batch processing. This could be a file reference in a PVsyst-defined format.
   • User-defined/imported shading factor tables could be used in other projects for site characterization and evaluating different scenarios in development. 

Plants are getting larger, and when modeling trackers with terrain, the simulations times can be quite large, but when using fast mode, the overestimation is not always acceptable depending on the purpose of the simulation.