Changes since version 1.2:
* Implement the Emacs 21 (:eval FORM) and (:KEYWORD ...) constructs;
handle unbound symbols in SYMBOL and (SYMBOL THEN [ELSE]) constructs;
use (cadr ...) instead of (car (cdr ...)).
;; Emacs 22 provides the format-mode-line function, which obsoletes
;; this package.
;; But Emacs 21 doesn't provide distinct functions for (1) generating
;; a string from `mode-line-format' and (2) displaying it in the mode
;; line. In src/xdisp.c, display_mode_element() does both, and it
;; doesn't have a Lisp binding. apply-mode-line-format.el defines an
;; eponymous Lisp function that returns any `mode-line-format' template
;; as a string.