New codes for Windows 95 keys + Japan:

               PS2         low level     internal (decimal)
Windows Left:  E0 1F     key: 68          125 [INKEY -126]
Windows Right: E0 27          69          126 [INKEY -127]
Menu:          E0 2F          6A          127 [INKEY -128]
No convert:    67             6B          109 [INKEY -110]
Convert:       64             6C          110 [INKEY -111]
Kana:          13             6D          111 [INKEY -112]
Yen/Bar:       6A             1D          46  [INKEY -47]
\ _:           51             6E          95  [INKEY -96]

The bottom row of a Japanese W95 keyboard goes:

Ctrl  Win  Alt  No convert  Space  Convert  Kana  Alt  Win  Menu  Ctrl

The Yen/Bar key is to the left of backspace (ie where the £ sign was
on Archimedes keyboards). It hence resurrects the old 1D low level code.
(The current PS2Driver doesn't know about this key).

The \ _ key is to the left of the right shift key (analogous to the \ |
key on UK keyboards). It has its own PS/2 scan code, hence I've decided
to give it its own RISC OS codes, rather than borrowing the \ | code,
as there is no reason why a keyboard couldn't have both of these keys.
