Make regex more sensible, improve performance on long lines
Fixed #7: `html` should be a property, not a method
Fixed #15: Improve regex in `html()` method, with thanks to Sani
Added XML property to output code without cleaning for HTML
XML style attributes are now converted to HTML style attributes
Fixed #14 Filter HTML into XML upon loading document
DOMTemplate is now more lax on what it accepts as HTML, various XML conversions are run to make it ready for PHP DOM:
* HTML entities decoded to unicode
* Elements that require it are self-closed (e.g. `<img>` -> `<img />`)
* HTML valueless attributes are converted to XML, i.e. `<a attr>` -> `<a attr="attr">`
* Script elements are escaped with XML CDATA blocks
These XML-isms are reversed when outputting as HTML
Removed the individual `html` and `xml` properties. To output cast the template object to a string, i.e. `echo $template;`.

The benefit is that it's stricter; when there are getters, users expect setters and you can only set the source code on instantiation.
Fixed empty `<title>` element producing invalid output