(edebug-window-live-p): Always alias to window-live-p.

(edebug-window-live-p): Always alias to window-live-p.
(edebug-set-conditional-breakpoint): Unconditionally use
the former Emacs >=19 definition.
(edebug-mark): Define unconditionally.
(edebug-eval-expression): Always call read-from-minibuffer
and specify history list.
(edebug-lemacs-specific): Override emacs-mark, edebug-window-live-p,
edebug-set-conditional-breakpoint.
(edebug-emacs-version-specific): Function deleted;
do the job at top level.
(edebug-emacs-19-specific): Function deleted, this is the default.