Support to raw 256 X-term-colors by adding init_color_pair function a UInt8 orverload

[habdig7oficial]

Hello as I pointed in #21 issue I'm having trouble with colors in a 256 X-term-color terminal, here are some small modifications, that allow use UInt8 values for init_color_pair directly. If you analyze, and think the changes are good this pull request is already made 😀 and if not I await yours ideas in the issue