Minor issue: Should we allow gesture to be a gesture specification as well as just a gesture
name? It simplifies its use by avoiding a profusion of defined gesture names, but we may want
to encourage the use of gesture names. | SWM

documentation is a documentation string, which can be used as documentation for the keystroke
accelerator.

If the command menu item associated with gesture is already present in the command table's
accelerator table and errorp is true, then the command-already-present error will be signalled.
When the item is already present in the command table's accelerator table and errorp is false,
the old item will first be removed.

=> remove-keystroke-from-command-table command-table gesture &key (errorp t) [Function]
Removes the command menu item named by keyboard gesture name gesture from command-
table's accelerator table. command-table is a command table designator.

If the command menu item associated with gesture is not present in the command table's menu
and errorp is true, then the command-not-present error will be signalled.

=> map-over-command-table-keystrokes function command-table [Function]
Applies function to all of the keystroke accelerators in command-table's accelerator table. func-
tion must be a function of three arguments, the menu name (which will be nil if there is none),
the keystroke accelerator, and the command menu item; it has dynamic extent. command-table
is a command table designator.

map-over-command-table-keystrokes does not descend into sub-menus. If the programmer
requires this behavior, he should examine the type of the command menu item to see if it is
:menu.