Allow posting links in comments.

There was an opts parameter which attempted enabling sencha.com/* URL-s,
but this option wasn't used anywhere the function was called from -
besides the option didn't work because some code before it attempted
turning all URL-s into links, but mistakenly also picked up URL-s
within href="...".

Anyway, I see no reason to only allow links to sencha.com, so allowing
all links, whatever they may be.

The code for convering URL-s to links is not needed at all because the
'marked' module does this already.