Add edgetrigger and oneshot event types

io.c

@@ -60,6 +60,12 @@ int uev_io_init(uev_ctx_t *ctx, uev_t *w, uev_cb_t *cb, void *arg, int fd, int e
  */
 int uev_io_set(uev_t *w, int fd, int events)
 {
+
+  if( events & UEV_ONESHOT 
+      && 1 == w->active ) {
+    return uev_watcher_rearm(w);
+  }
+
 	/* Ignore any errors, only to clean up anything lingering ... */
 	uev_io_stop(w);