Use window interior/exterior shading types

[joseph-robertson]

• Introduce window_interior_shading_type, window_exterior_shading_type, and window_insect_screens to the lookup but set them all to auto

You might consider using them instead of summer/winter coefficients. They interact with window type (SHGC), whereas the coefficients have no interaction. Though it will be a definite change from what ResStock is doing today.

Originally posted by @shorowit in #1298 (comment)