Integrated Emacs 19.34 and XEmacs 19.15

Integrated Emacs 19.34 and XEmacs 19.15
corrections (typos, style, command revisions, etc).
Integrated hacked up XEmacs immediate keybindings display.  See
`icomplete-show-key-bindings', `icomplete-get-keys', and
`icomplete-completions'.  Doesn't work with mainline GNU
Emacs 19.34 (because the cmdloop doesn't set owindow, and the
current-local-map doesn't take optional buffer arg), so feature
is, by default, inhibited unless we're running in XEmacs.
(icomplete-get-keys): Return keys bound to func name in buffer
"owindow" - since "owindow" is calling-buffer history present
only in XEmacs, this function is only useful in XEmacs.
(icomplete-max-delay-chars, icomplete-compute-delay): New vars.
(icomplete-delay-completions-threshold): New var.
These customize the delay behavior, so that completions don't
intrude as quickly for short input.