PostgreSQL support

here is the code to allow this module to be installed in postgresql environment

      db_query("CREATE TABLE search_index_queue (
        nid serial PRIMARY KEY,
        module character(60) NOT NULL,
        \"timestamp\" integer NOT NULL
      )");
      
      
      db_query("CREATE TABLE search_fuzzy_index (
        id serial PRIMARY KEY,
        nid integer NOT NULL,
        word_id integer NOT NULL,
        ngram varchar(6) NOT NULL,
        completeness double precision NOT NULL,
        score numeric(8,2) NOT NULL
      )");