proper use of Misaka's HTML render flags (fix malicious HTML injection)
proper use of Misaka's HTML render flags (fix malicious HTML injection)

This commit now sanitizes *all* HTML tags written by the user (also
prevents auto-link to "unsafe" web protocols and images) as intended.

Fortunately because of Sundown's typography support, it did not affect
JS injection, but custom style tags and iframes.

PS: thanks to the anonymous submitter of a comment including a style tag
for 24pt, red font ;-)

janusnic/isso,jiumx60rus/isso,posativ/isso,jelmer/isso,WQuanfeng/isso,princesuke/isso,mathstuf/isso,xuhdev/isso,janusnic/isso,jelmer/isso,mathstuf/isso,xuhdev/isso,Mushiyo/isso,princesuke/isso,commentedit/commented.it,posativ/isso,commentedit/commented.it,xuhdev/isso,princesuke/isso,commentedit/commented.it,jiumx60rus/isso,Mushiyo/isso,posativ/isso,WQuanfeng/isso,posativ/isso,mathstuf/isso,jelmer/isso,janusnic/isso,jiumx60rus/isso,WQuanfeng/isso,jelmer/isso,Mushiyo/isso,Mushiyo/isso,commentedit/commented.it