panic() cleanup.

this change
   - makes panic() variadic, doing full printf() formatting -
     no more NO_NUM, and no more separate printf() statements
     needed to print extra info (or something in hex) before panicing
   - unifies panic() - same panic() name and usage for everyone -
     vm, kernel and rest have different names/syntax currently
     in order to implement their own luxuries, but no longer
   - throws out the 1st argument, to make source less noisy.
     the panic() in syslib retrieves the server name from the kernel
     so it should be clear enough who is panicing; e.g.
         panic("sigaction failed: %d", errno);
     looks like:
         at_wini(73130): panic: sigaction failed: 0
         syslib:panic.c: stacktrace: 0x74dc 0x2025 0x100a
   - throws out report() - printf() is more convenient and powerful
   - harmonizes/fixes the use of panic() - there were a few places
     that used printf-style formatting (didn't work) and newlines
     (messes up the formatting) in panic()
   - throws out a few per-server panic() functions
   - cleans up a tie-in of tty with panic()

merging printf() and panic() statements to be done incrementally.

kernel/system/do_safecopy.c

@@ -350,7 +350,7 @@ PUBLIC int do_safecopy(struct proc * caller, message * m_ptr)
 		src_seg = m_ptr->SCP_SEG;
 		dst_seg = D;
 		access = CPF_WRITE;
-	} else minix_panic("Impossible system call nr. ", m_ptr->m_type);
+	} else panic("Impossible system call nr.: %d", m_ptr->m_type);
 
 	return safecopy(caller, m_ptr->SCP_FROM_TO, caller->p_endpoint,
 		(cp_grant_id_t) m_ptr->SCP_GID, src_seg, dst_seg,