Removed various brightness modes and made highest brightness into Direct mode. Can use relative intensity to set brightness, ie RGB(255,0,255) (magenta) at ~60% brightness is RGB(150,0,150)

(cherry picked from commit b43cfd3b04e9faf980e319c596be5de49140f9b0)
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Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f