Add <compatibility> notes for changes made in version 2.4.3 + fix some...

Add <compatibility> notes for changes made in version 2.4.3 + fix some formating + backport things in trunk

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1586447 13f79535-47bb-0310-9956-ffa450edef68