add lightline color scheme

[sainnhe]

This color scheme is awesome, and I creat this PR to add support of lightline. Here is the preview:

[karoliskoncevicius]

I don't use any status line plugins, but looks good to me. Might install it just to test how it looks. Thanks!

[karoliskoncevicius]

I adjusted the colors a bit, because the designed used some colors outside the colorscheme and in addition some choices were out of sync with other highlighted elements (like visual being displayed in yellow, when the visual selections are blue in this scheme).

Otherwise all seem to be working, noted your contribution in the README. Thank you again!

[sainnhe]

@KKPMW Thanks, I have tried in my machine, it looks great!
BTW, the highlight elements(like visual being displayed in yellow, insert in green, normal in blue) is from nova lightline color scheme, because I thought this color scheme is very similar to nova.