textmodex/{ispell,flyspell}.el: Decrease XEmacs incompatibilities.

textmodex/{ispell,flyspell}.el: Decrease XEmacs incompatibilities.

* flyspell.el:
  (flyspell-check-pre-word-p): Use `string-match'.
  (flyspell-delete-region-overlays): Use alternative definition for XEmacs.
  (flyspell-delete-all-overlays): Use `flyspell-delete-region-overlays'.
  (flyspell-word): Use `process-kill-without-query' if XEmacs.
  (flyspell-mode-on): Use `interactive-p' if XEmacs.
  (flyspell-incorrect-face, flyspell-duplicate-face):
  Do not use `define-obsolete-face-alias' under XEmacs, but old method.

* ispell.el:
  (ispell-with-no-warnings): XEmacs alternative `with-no-warnings'
  definition or Emacs alias.
  (ispell-command-loop, ispell-message): Use `ispell-with-no-warnings'.
  (ispell-word): Do not use `region-p' if XEmacs.