Kernel changes:

- reinstalled priority changing, now in sched() and unready()
- reinstalled check on message buffer in sys_call()
- reinstalled check in send masks in sys_call()
- changed do_fork() to get new privilege structure for SYS_PROCs
- removed some processes from boot image---will be dynamically started later

kernel/type.h

@@ -18,7 +18,7 @@ struct system_image {
   int priority;				/* scheduling priority */
   int stksize;				/* stack size for tasks */
   char call_mask;			/* allowed system calls */
-  long send_mask;			/* send mask protection */
+  bitchunk_t send_mask;			/* send mask protection */
   char proc_name[P_NAME_LEN];		/* name in process table */
 };