Add `touch-end' event type

Add `touch-end' event type

* etc/NEWS:
* doc/lispref/commands.texi (Misc Events): Document new
`touch-end' event type.

* lisp/bindings.el: Ignore touch-end events by default.

* src/keyboard.c (make_lispy_event): Add support for
TOUCH_END_EVENT events.
(syms_of_keyboard): New symbol `touch-end'.

* src/termhooks.h (enum event_kind): New member
`TOUCH_END_EVENT'.

* src/xterm.c (handle_one_xevent): Send touch-end events when
appropriate.