/*
 * Monitor a directory.
 *
 * Returns a Fam::Request object, which is used to identify the monitor
 * associated with events.
 *
 * Aliases:
 *   Fam::Connection#monitor_dir
 *   Fam::Connection#directory
 *   Fam::Connection#dir
 *
 * Examples:
 *   req = fam.monitor_directory '/tmp'
 *
 */
static VALUE fam_conn_dir(VALUE self, VALUE dir) {