Add --color=[dark|light|16|bw] option

- dark:  the current default for 256-color terminal
- light: color scheme for 256-color terminal with light background
- 16:    the default color scheme for 16-color terminal (`+2`)
- bw:    no colors (`+c`)

CHANGELOG.md

@@ -9,6 +9,10 @@ CHANGELOG
 - Performance optimization
 - Less aggressive memoization to limit memory usage
 
+### New features
+
+- Added color scheme for light background: `--color=light`
+
 0.9.9
 -----