Add the tiger source code bundle from the book site

Signed-off-by: jmug <u.g.a.mariano@gmail.com>

tiger/chap7/temp.sig

@@ -0,0 +1,11 @@
+signature TEMP = 
+sig
+  eqtype temp
+  val newtemp : unit -> temp
+  structure Table : TABLE sharing type Table.key = temp
+  val makestring: temp -> string
+  type label = Symbol.symbol
+  val newlabel : unit -> label
+  val namedlabel : string -> label
+end
+