Lexicon lookup sometime is ambiguous

[giuliopaci]

Current lexicon lookup implementation with POS tags is ambiguous.
The token "dell'X" is found in the lexicon because the word "dell'" is in the lexicon with POS tag "X". A solution is to change the code so that a # is always inserted between the word and the POS and that # and \ are escaped with a \ for both the POS and the word.