fieldsets, legends, labels in forms

The changes in this submission are:
* the file as a whole now is in UTF-8 instead of Windows codepage Cp1252 (or ISO 8859-x);
* the file now has a proper HTML5 "doctype";
* the page now has a title element (so bookmarks get a useful title, too);
* form fields have been grouped in fieldsets with legends;
* radio buttons now have labels, so you have a larger click area (you can click the label to select the radio button;
* some validation errors were correct (e.g. br elements without a > at the end).

The h2 headings are still there although they strictly speaking duplicate some of the legends in the fieldsets.
HTTP responses no mostly real HTML instead of txt

Most of the results pages (response.write(...), e.g. for logging, setting a matchmaker, etc) sent plain text as an HTML response. I changed this for most responses.
Merge branch 'cstrobbe-patch-1'