fix: use the cache in check_thread() as well to avoid huge amounts of queries
fix: not only load close votes, but also open votes
workaround: show error messages with position:fixed
more performance optimizations

might not lead to a performance gain when used with default values, but
will lead to a performance gain when used with differing configuration
performance optimizations for open/close votes

Now we're able to query both votes with one query (and thus, when
returning more than one message, with one query at all instead of one
query per message)
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