Clicking 'ok' button on a dialog form fires 'submit' event.

Takes effect if the '.txp-dialog' is used on a form element.
Clicking the 'Ok' button sends the form and allows
capturing the submit event without having to worry about
jQuery UI or the dialog logic, or having to overwrite the
button definitions.

git-svn-id: http://textpattern.googlecode.com/svn/development/4.x@5179 2fea6a4d-a838-0410-917b-93a53c48e9d2
Few spaces.

git-svn-id: http://textpattern.googlecode.com/svn/development/4.x@5180 2fea6a4d-a838-0410-917b-93a53c48e9d2
Merge remote-tracking branch 'upstream/master'