Add support to diacritic insensitive search in CPString rangeOfString:options:range: method

When searching by range, the option of diacritic insensitive search was not being contemplated

Also add support to strip variants of 'E' 'I' 'O' 'U' that were not implemented.
Source: http://www.ascii-code.com/
Merge pull request #2203 from sbalay/dev

Add support to diacritic insensitive search in CPString rangeOfString:options:range: method