Added a single conversion from key code 219 to XK_bracketleft so that ctrl-[
passes through noVNC into the server session. This is useful for editing with
vi/vim as ctrl-[ acts as the ESC key but allows one to leave their fingers on
the home row.
Mouse wheel event handling has now been standardised and has broad
support. Use this event rather than the older, non-standard ones.
At the same time fix up support for horisontal mouse wheel events.
This commit moves all the input-related files from `core/`
to `core/input/`, and renames a couple as relevant
(input.js --> input/devices.js, keyboard.js --> input/util.js).
mmead