clean up the query from non-letter characters

app/query_parser.rb

···
 
     while match = query.match(/".+?"/)
       range = match.begin(0)...match.end(0)
-      phrase = query[range][1..-2].strip
+      phrase = query[range][1..-2].gsub(/[\W_]+/, ' ').strip
       query[range] = ' '
       @terms << phrase
     end
 
-    @terms += query.split(/ +/)
+    @terms += query.gsub(/[\W_]+/, ' ').strip.split(/ +/)
   end
 end