sanitize the content of the text after converting geonext specific parts to enable the use of value tags from jessiecode
added two text attributes: parse and useCaja.

parse can be used to declare strictly static texts. Setting these texts' content with a string won't trigger the jc/gxt parsers and instead just use the plain string (maybe sanitized if set from within jc).

useCaja gives the author the choice if he wants to use the caja html_sanitizer or our strict angle bracket replaced.

The board infobox is now a static text (parse attribute set to false) which speeds up dragging.