It stores both the konst selection value for alpha and color channels (for two tev stages per ksel), and half of a swap table row (there are 4 total swap tables, which can be used for swizzling the rasterized color and the texture color, and indices selecting which tables to use are stored per tev stage in the alpha combiner).  Since these are indexed very differently, the old code was hard to follow.

Adds a pass to process driver deficiencies between UID caching and use, allowing a full view of the whole pipeline, since some bugs/workarounds involve interactions between blend modes and the pixel shader

Avoids placing generic names in the surrounding namespace.

SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.