Fix where Edwin leaves the cursor in console-screens.

Fix where Edwin leaves the cursor in console-screens.

toggle-read-only and the set-mark-command leave the terminal's cursor
in the modeline or minibuffer (respectively).

* src/edwin/buffrm.scm (window-direct-output-cursor!): New procedure.

* src/edwin/bufwiu.scm (buffer-window/direct-output-cursor!): New procedure.

* src/edwin/edwin.pkg: Export window-direct-output-cursor! to (edwin)
for screen code like console-wrap-update!.  Export
editor-frame-cursor-window to (edwin screen) for screen-cursor-window.

* src/edwin/screen.scm (screen-cursor-window): New procedure.

* src/edwin/tterm.scm (console-wrap-update!): Leave the terminal's
cursor in the screen-cursor-window.
(output): Do not die when screen-cursor-y is still #f -- found when
interpreting Edwin.