slideview: Purify item html when output
slideview: Gather html purify treatment to Gregarius::HtmlFix()
slideview: Add optional html purify method using htmLawed

htmLawed:
http://www.bioinformatics.org/phplabware/internal_utilities/htmLawed/
Put it in php_include path, eg: 'htmLawed/htmLawed.php'

Another possible choice is HTML Purifier: http://htmlpurifier.org/
may giv it a try someday.