All cases from greek alpabet considering diacritic marks

[Nick-]

I wasn't sure where to post this, in case there is an interest for the inclusion of greek letters in the ignoring diacritic marks list but no knowledge of greek alphabet, there are basically 6 cases:

Έ,έ => ε
Ύ,ύ => υ
Ί,ί   => ι
Ό,ό => ο
Ά,ά => α
Ή,ή => η

[boroda]

just in case Steven wants to add support for new diacritic marks:

for Russian

ё => е
Ё => Е

[Steven]

i have added those for the next update