Use multibyte-safe case convertion

[Koc]

No description provided.

[florianeckerstorfer]

Did you encounter any problems because strtolower() was used? In theory this should not matter because the rules are applied first and there should only be ASCII characters in the string at this point.

[Koc]

It doesn't works correctly for russian slugs that used utf-8

[florianeckerstorfer]

Ok, because the Russian characters are not transliterated?

[Koc]

As you see from transliteration rules we should duplicate rules for capital and small letters

'Щ' => 'Shch',
'щ' => 'shch',

It is ok, but when we add rules for 2 charachters, like

<call method="addRule">
    <argument>ый</argument>
    <argument>yi</argument>
</call>
<call method="addRule">
    <argument>дж</argument>
    <argument>j</argument>
</call>

it is so hard, because we should add rules for дж, ДЖ, Дж etc