Revert / Modify PR #104

[lygamac]

The solution in PR #104 is not a viable solution for all users (there might be users using dark terminal with light colorscheme or vice-versa, or a different theme with makes the color incoherent.)

Suggestion, add:

if (&background == dark)
    " dark theme color codes
elseif (&background == light)
    " light theme color codes
endif 

The only drawback of this is to reload the plugin in order to perform an if check if the user switches the background.

[lygamac]

Solved by #120