Changes:
* EMU-ELS (emu-modules): Add setting for GNU Emacs 23 or later.
* invisible.el: In GNU Emacs 23, inv-19.el overrides builtin
function `invisible-p'. To fix the bug, require `inv-23' when
running with GNU Emacs 23 or later.
* poe.el (format-time-string): Fix problem on GNU Emacs 22.2
Many small changes which enhance APEL's functionality. Due to the
charasteristic of APEL as a portability layer of emacsen, no user visible
change, but more portability, possibly.
