Read hex scalar values

TODO

@@ -27,7 +27,7 @@ Tier 1:
     - fib.scm
     - gcbench.scm - Needed to manually import (srfi 9)
     - graphs.scm
-    - lattice.scm - Error: run: unanticipated problem size 44. may be a problem with numbers and (case)
+    - lattice.scm
     - matrix.scm
     - mazefun.scm
     - maze.scm - There is a problem reading the input file

scheme/read.sld

@@ -437,6 +437,9 @@
          (integer->char 32))
         ((equal? buf '(#\t #\a #\b))
          (integer->char 9))
+        ((and (> (length buf) 1)
+              (equal? (car buf) #\x))
+         (integer->char (string->number (list->string (cdr buf)) 16)))
         (else
          (parse-error (string-append 
                         "unable to parse character: "