wiki toc generates invalid links on non-latin only symbols (headings) (BB-487)

In wiki <<toc>> command generate links by use only latin symbols, it is wrong when we have headings which contains only non-latin symbols.

For example, for heading == Q1Заголовок == - it generates #Q1 link. But for heading == Заголовок == it generates empty (after '#' char) link.

PS: Sorry for my bad english.