New function: remplace_special().

Replace special characters by '-' (by default) (you can change it on :11 self.replacement_char)
And replace Latin-1 characters by a basic.
e.q.:
my_unicode_str = u'#HÉLLØ, Comment ça va ?#'
nyanparser.NyanParser().remplace_special(my_unicode_str)
return: HELLO--Comment-ca-va--