use multibyte substring for UTF-8 safe operations

[crossan007]

this should close the specific issue mentioned in #1282, but there is more work for full UTF8 compliance.

[dleigh]

Just to let you know, in the Directory Report free-form input text box at the bottom, diacritic accents are NOT handled well. Here's the text I put in:

Les membres actuels du conseil sont : Nadine Adriano, Isabelle Beck, Denis Bouchet, Huguette Brand, Luc et Manuela Bussière (couple pastoral), Stéphan Haffner, David et Angela Leigh, Vito et Jocelyne Pascazio et Alana Smith

Here's what came out:
Les membres actuels du conseil sont : Nadine Adriano, Isabelle Beck, Denis Bouchet,
Huguette Brand, Luc et Manuela Bussière (couple pastoral), Stéphan Haffner,
David et Angela Leigh, Vito et Jocelyne Pascazio et Alana Smith

Also if I put in multi-line text, such as:
Les membres actuels du conseil sont :
Nadine Adriano
sabelle Beck
Denis Bouchet
Huguette Brand
Luc et Manuela Bussière (couple pastoral)
Stéphan Haffner
David et Angela Leigh
Vito et Jocelyne Pascazio
Alana Smith

I get this:
Les membres actuels du conseil sont : \r\nNadine Adriano\r\nsabelle Beck\r\nDenis
Bouchet\r\nHuguette Brand\r\nLuc et Manuela Bussière (couple
pastoral)\r\nStéphan Haffner\r\nDavid et Angela Leigh\r\nVito et Jocelyne
Pascazio\r\nAlana Smith

This doesn't matter whether I put it into this screen or into the system config screens or directly into the database using phpmyadmin (I've not tried raw SQL and don't particularly want to go there).