remove support for deprecated numerical 4bpp color values
remove support for deprecated numerical 4bpp color values

Now color values have to be "typed" via the ColorNNN types.

Hzj-jie/koreader-base,apletnev/koreader-base,Frenzie/koreader-base,frankyifei/koreader-base,houqp/koreader-base,koreader/koreader-base,apletnev/koreader-base,Frenzie/koreader-base,houqp/koreader-base,koreader/koreader-base,Frenzie/koreader-base,NiLuJe/koreader-base,Hzj-jie/koreader-base,NiLuJe/koreader-base,frankyifei/koreader-base,koreader/koreader-base,apletnev/koreader-base,NiLuJe/koreader-base,apletnev/koreader-base,houqp/koreader-base,koreader/koreader-base,Frenzie/koreader-base,frankyifei/koreader-base,frankyifei/koreader-base,Hzj-jie/koreader-base,NiLuJe/koreader-base,houqp/koreader-base,Hzj-jie/koreader-base