(custom-known-themes): New variable.

(custom-known-themes): New variable.
(custom-declare-theme): New function.
(deftheme): New macro.
(custom-make-theme-feature): New function.
(custom-theme-p): New function.
(custom-check-theme): New function.
(custom-push-theme): New function.
(custom-theme-set-variables): Take themes into account.
(custom-loaded-themes): New variable.
(custom-theme-loaded-p): New function.
(provide-theme): New function.
(require-theme): New function.
(custom-remove-theme): New function.
(custom-do-theme-reset): New function.
(custom-theme-load-themes): New function.
(custom-load-themes): New function.
(custom-theme-value): New function.
(custom-theme-variable-value): New function.
(custom-theme-reset-internal): New function.
(custom-theme-reset-variables): New function.
(custom-reset-variables): New function.