fixed safe_html for inline alerts

moved display code for alerts into a helper.
Ported back the safe_join that will escape the parts and mark as html_safe
made wiki preview html_safe
try(:method) now returns nil and < does not work on that - fixes #4216
redirect to /me if logged_in - fixes #4144
disabled filters referred to undef label - refs #4255
only list discussions with some post on /me/discussions - refs #4255