reimplemented synonym searching

Jason M. (jmielens) and I added a new actor (SynonymStreamReplier) that does synonym-based searching. We get two words from an incoming tweet, and get up to 5 synonyms each, including the word itself. See tshrdlu.util.English to see the new "synonymize" function that we use for this (Note our new "synonymize" is different because it takes an additional argument; your original synonymize function is unchanged). Matched tweets must contain one synonym of each of the two words.