Din's Legacy patch 0.903 — Din's Legacy Steam update #671576

This patch optimizes a bunch of things (test scene ~32% faster), adds a model for the tower entrance, and fixes a bunch of smaller issues. 0.903 change list: now cull minimap blips better (test went from 57.7 to 65.4 fps, 13.3%) removed an extra height calculation in GraphicsSystem::shouldCullModel (test went from 64.3 to 67.9 fps, 5.6%) removed lightIndexes being a local array in renderSurface (test went from 54.3 to 56.7 fps, 4.4%) culled some more minimap blips better (test went from 69.2 to 71.5 fps, 3.3%) made getTileObject caching work better (test went from 57.8 to 58.9 fps, 1.9%) cache model matrix instead of just angle (test went from 78.4 to 79.8 fps, 1.8%) changed a couple dynamic_cast to static_cast (test went from 79.0 to 80.3 fps, 1.6%) no longer cull each surface separately (now per entity) (test went from 48.3 to 49.0 fps, 1.5%) sped up surface culling in calculateShadowM...