Colorschemes define colors for specific contexts.
Generally, this works by passing a set of keywords (strings) to
the colorscheme.get() method to receive the tuple (fg, bg, attr).
fg, bg are the foreground and background colors and attr is the attribute.
The values are specified in ranger.gui.color.
A colorscheme must...
1. be inside either of these directories:
2. be a subclass of ranger.gui.colorscheme.ColorScheme
3. implement a use(self, context) method which returns (fg, bg, attr).
context is a struct which contains all entries of CONTEXT_KEYS,
associated with either True or False.
define which colorscheme to use by having this to your options.py:
from ranger import colorschemes
colorscheme = "name"