GPU option for shadows #2
Description
Adds GPU implementation of shadows (from Rust) which gives a roughly 30+ speedup for the test dataset.
Also speeds up calling functions e.g. SVF and SOLWEIG though not as dramatically.
shadowingfunction_wallheight_23: min=0.815s, max=0.834s, avg=0.825s
--- Testing with GPU disabled (CPU only) ---
shadowing.calculate_shadows_wall_ht_25 (CPU): min=0.084s, max=0.086s, avg=0.084s
--- Python vs Rust comparison ---
Relative speed: 9.76 times faster for given data.
--- Testing with GPU enabled ---
shadowing.calculate_shadows_wall_ht_25 (GPU): min=0.020s, max=0.039s, avg=0.026s
--- Python vs Rust + GPUcomparison ---
Relative speed: 31.19 times faster for given data.