#193 Search export to CSV breaks UTF8 Summaries

[titmouse]

version 2.6.4

On the ticket search page there is a button "Export Results". It saves search results to CSV file in UTF8. Russian ticket Subject fields got cut like this:
angagement.ru: еще на конкурс, хоть он уже закончился
exports as:
angagement.ru: еще на конкурс, хот�

Short Subjects exported fine. I tracked down the problem till line 50 in exportSearch.php:
$v = humanReadableValue($k,$v);

If I comment this line it fixes the problem. So the bug is -- function humanReadableValue() do not respect long UTF-8 strings.