Disiallow Voice Crowding (#5)

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This setting, when checked, will prevent voiceless consonant from being placed between a voiced consonant and a vowel. The default state is checked.

if (preventCrowding && lastletter.Voiced)
{
    var unvoiced = acceptable.Where(x => !x.Voiced).ToList();
    foreach (var v in unvoiced)
        acceptable.Remove(v);
}