Implemented async comm buffers (but probably not bugfree), and along
with them, the functionality of async event notifications, mong them
EnableCommNotification. Removed a previous hack that was faking the
buffers, since we now have real buffers...

diff --git a/include/comm.h b/include/comm.h
index 3cd3ba4..d1c1478 100644
--- a/include/comm.h
+++ b/include/comm.h
@@ -7,13 +7,14 @@
     char *devicename;   /* /dev/cua1 */
     int fd;
     int suspended;
-    int unget;
-    int unget_byte;
+    int unget,xmit;
     int baudrate;
     /* events */
     int commerror, eventmask;
     /* buffers */
     char *inbuf,*outbuf;
+    unsigned ibuf_size,ibuf_head,ibuf_tail;
+    unsigned obuf_size,obuf_head,obuf_tail;
     /* notifications */
     int wnd, n_read, n_write;
 };