Moved MH-E image files from toolbar and mail directories into
etc/images.
* mail/reply2.*: Moved to etc/images/mail/reply*.
* toolbar/execute.*, toolbar/highlight.*, toolbar/mh-logo.xpm:
* toolbar/page-down.*, toolbar/show.*, toolbar/widen.*: Moved to
etc/images.
* toolbar/alias.*, toolbar/refile.*, toolbar/repack.*:
* toolbar/reply*: Moved to etc/images/mail.
* toolbar/rescan.*: Moved and renamed to etc/images/refresh.*.
* mh-e/mh-customize.el (mh-refile-msg, mh-tool-bar-reply-from)
(mh-tool-bar-reply-to, mh-tool-bar-reply-all)
(mh-alias-grab-from-field, mh-pack-folder): Image files moved to
etc/images/mail so added "mail/" prefix.
(mh-reply): Ditto. Also renamed reply2.* to reply.*.
(mh-rescan-folder): Ditto. Renamed image file to refresh.* since
it can be used in the general sense. Does not have "mail/" prefix.
