Some web-servers, e.g. thttpd, seem to do a form of canonical reverse DNS look-up before presenting HOST_NAME environment variable. As a consequence, the host name may not be the same as in the URL and may also present case variations according to what is recorded in the (local) DNS. Moreover, standard says host name should be taken case-insensitive.
Test cases have lead to non-identification of tree in configuration file because of this behaviour. Also, speed switch buttons contain faulty URL.
Host name comparison should always be case-insensitive. This impacts subroutines _initialize and treeurl in Config.pm.