Template title tags shouldn't ignore the prefix,even if 'display' is false

[yoavf]

Some template title tags that accept both the $prefix and $display paramater ignore the prefix if the display is set to false, i.e. single_post_title(), single_term_title().

Some don't, i.e. single_month_title().

It doesn't make sense to ignore the prefix - if the developer doesn't want it, he can leave it empty.

Yes, I have detected the same bug. The prefix must be also included if display is set to false.