sql/ha_federated.cc:
  added code to handle multi-keys (per monty). This code still fails to compile because sql_analyse.cc's method, append_escaped only accepts two string pointers. I don't know if append_escaped will be overloaded to accept string pointer, byte/char pointer, and length, as is being passed in this example. Need to talk to devs/monty about this.
sql/ha_federated.h:
  added method declaration of create_where_from_key