New color replacement methods!

  Changes:
    - Find and replace fields from color.inc inside stylesheets. /* {{base}} */ #ffffff /* {{/base}} */
    - Include a 'base' field if you want to change colors of non-tagged color values. (I.e. Garland)
    - You can keep the above stylesheets in the /color folder by doing: 'css' => array( 'color/style.css',),
    - Fixed bug w/ blend_target storing in DB
    - Added some more logic for falling back to default themes/color theme changing
 
  Quirks:
    - In listthemes(), must check if theme is enabled in system! This shows extra color-enabled themes in user/{uid}/edit
    - When changing over a theme, the old scheme name may show in selectbox (the module will still correctly move to default scheme for newly selected theme, though)