a10-tpr3-html-report: Add '--notitle' option

Useful in the case if we want to just copy-paste html tables to
mediawiki and are not interested in the title header with links
and explanations.
a10-tpr3-html-report: HTML escape the memtester error log

The memtester error log may contain just about anything, including
bad &, ', " characters and even stray html tags. So it needs to be
escaped.
a10-tpr3-html-report: Add missing '<p>' tag