New codes for Windows 95 keys + Japan:

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

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 \ _ 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.
