Better handling of emacsclient, updated

I've taken @ahyatt's changes from https://github.com/sellout/emacs-color-theme-solarized/pull/17 and have applied them to my branch, with some updates.  Full list of changes:

* Remove solarized-degrade (from ahyatt)
* Put nil in 5th column of solarized-colors for base00 and base0 so that they don't change in 8-color mode
* New function solarized-face-for-index (from ahyatt)
* New function solariezd-flip (from ahyatt)
* New function solarized-faces (from ahyatt)
  * Vary color for different terms in face specs only (from ahyatt)
  * Reverse light/dark logic to match upstream
  * Add support for 8-color terms
  * Support solarized-broken-srgb
* solarized-color-definitions: Start with faces from upstream and apply ahyatt's changes:
  * Replace light case with generic URL in documentation
  * Consolidate let-bound lists with let* to reduce indentation
  * Don't let-bind yellow and other colors
  * Use default and cursor faces instead of having separate list of attributes to set them
  * Add bright-bold, opt-under, back
  * Base faces are symbols, not let-bound variables
  * Change ((t (spec))) to just (spec) throughout
* No attempt has been made to support the solarized-contrast high case due to lack of time.  Perhaps a 6th column in
  solarized-colors would be a better approach than rotatef on existing colors.
* No attempt is made to set background-mode; perhaps it is unnecessary since full face definitions are provided