Fixed various spelling errors.

original commit: c9519fd11300b07292df8619e86f48533eff6e4d

collects/parser-tools/lex.rkt

@@ -252,7 +252,7 @@
                                       ;; including a match at the current state
                                       (longest-match-action 
                                        (vector-ref actions start-state))
-                                      ;; how many bytes preceed char
+                                      ;; how many bytes precede char
                                       (length-bytes 0)
                                       ;; how many characters have been read
                                       ;; including the one just read

collects/parser-tools/private-yacc/grammar.rkt

@@ -12,7 +12,7 @@
   (define-struct prod (lhs rhs index prec action) (make-inspector))
 
   ;; The dot-pos field is the index of the element in the rhs
-  ;; of prod that the dot immediately preceeds.
+  ;; of prod that the dot immediately precedes.
   ;; Thus 0 <= dot-pos <= (vector-length rhs).
   (define-struct item (prod dot-pos) (make-inspector))