Fixed a bug where attributes with the same string in braces would be
assigned the same value. For example Character Trigrams {his}, Function
Words {his} and Words {his} would all be assigned the same value (the
number of {his} trigrams) for the purposes of clusters. This is because
they all had the same name in the ArrayList that stored stripped
attribute names, so now the function that strips attribute names will
leave the type of feature (character trigram, POS tag, etc.) instead of
just the string in braces.
Also fixed a bug where attributes with 1 in their braces would not be
named correctly.