Add overloads to RemoveDiacritics and IsDiacritics extension methods to pass a IDiacriticsMapper

[toburger]

If you want to use the extension methods of the library you have to register a global default diacritics mapper.
This is not very pure and it does not allow to have different mappings for different strings without switching the global mapper.

StaticDiacritics.SetDefaultMapper(() =>
    new DiacriticsMapper(
        new MyGermanAccentMapping(),
        new GermanAccentsMapping(),
        new ItalianAccentsMapping(),
        new ArabicAccentsMapping()
    )
);

"Thöni".RemoveDiacritics() // "Thoeni"

The current "pure" approach is to instantiate a DiacriticsMapper with accent mappings and use the methods form this instance.

var myMapper = new DiacriticsMapper(
    new MyGermanAccentMapping(),
    new GermanAccentsMapping(),
    new ItalianAccentsMapping(),
    new ArabicAccentsMapping());

myMapper.RemoveDiacritics() // "Thoeni"

This is fine.
But it would be convenient to have an overload for the extensions methods where the mapper (or single accent mappings) could be passed:

"Thöni".RemoveDiacritics(myMapper) // "Thoeni"

or simply as a params array:

"Thöni".RemoveDiacritics(new MyGermanAccentMapping()) // "Thoeni"