Changed the filesystem proto file and enhanced the mkfs7 tool based on

Phi's analysis of the filesystem.

tools/proto

@@ -4,22 +4,25 @@
 #    filename f[r-][w-][r-][r-] uid local_file_to_insert
 #    dirname  d[r-][w-][r-][r-] uid [inumber]
 #    device   i[r-][w-][r-][r-] uid inumber
+#    link     l---- inumber
 #
 # The top directory's name is ignored
 # Numeric values are in decimal
 # Contents of each directory ends with a $ on a line by itself
 # Format was inspired by 6th Edition mkfs
 #
-dd 	     drw-- -1 2
-    system   drw-- -1 3
-	init frwr- -1 ../bin/init
+dd 	         drw-- -1 2
+    system       drw-- -1 3
+	init     frwr- -1 ../bin/init
+        ttyin    irwr- -1 6
+        keyboard irwr- -1 7
+        pptin    irwr- -1 8
+        ttyout   irwr- -1 10
+        display  irwr- -1 11
+        pptout   irwr- -1 12
+        sh       frwr- -1 ../bin/sh
 	$
-    ttyin    irwr- -1 6
-    keyboard irwr- -1 7
-    pptin    irwr- -1 8
-    ttyout   irwr- -1 10
-    display  irwr- -1 11
-    pptout   irwr- -1 12
+
     as       frwr- -1 ../bin/as
     cat      frwr- -1 ../bin/cat
     chmod    frwr- -1 ../bin/chmod
@@ -31,9 +34,10 @@ dd 	     drw-- -1 2
     ln       frwr- -1 ../bin/ln
     ls       frwr- -1 ../bin/ls
     mv       frwr- -1 ../bin/mv
-    sh       frwr- -1 ../bin/sh
     stat     frwr- -1 ../bin/stat
     ken      drwr- 10
+        system l---- 3
         $
     dmr      drwr- 12
+        system l---- 3
         $