Fix handling of pre-OS X Mac color names
Refactor color string to RGB code into autoloads

Expose 2 more functions as autoloads:
csapprox#common#color_name_to_hex(name)
  - Resolve a color name (like PapayaWhip) to hex (#ffefd5)

csapprox#common#hex_to_rgb(hex)
  - Split a hex color (like #ffefd5) to a list ([ 255, 239, 213 ])