Braille Lite Driver for BRLTTY (help screen)

Key bindings:

advance bar: full window left/right
1: line up
4: line down
23: keyboard up arrow
56: keyboard down arrow
2: keyboard left arrow
5: keyboard right arrow
3: window character left
6: window character right
235: line start
256: line end
123: top left
456: bottom left

125: home
14: toggle cursor tracking
124 chord: (un)freeze screen
1456: toggle help mode
34: toggle status mode
24: toggle attribute display

245 chord: route cursor to beginning of line
45 chord: route cursor to current line
236 chord: cut start
356 chord: cut end
1234 chord: paste

36: speak line
134: mute speech

25 chord: configuration options: menu, save or reset (cancel).
1235: restart Braille driver

Insist on chord for *dangerous* commands, i.e. routing, cut/paste etc.

INTERNAL:

g chord: position internal (alternate inversion?) cursor for routing or
  cutting.  Terminate with route, cutbeg, cutend or cancel.  To move
  cursor: chrlt, chrrt by 1; bar by (width+3)/4; lnbeg, home, lnend for
  beginning, middle and end of display.

k chord toggles keyboard emulation mode - initially off.
When on, unchorded characters passed directly to inskey(), unless prefixed
by:

u chord: uppercase (twice to lock)
q chord: unlock
x chord: control character
35 chord: meta or ALT (hardwire to `^[' for the time being)
z chord: cancel preceding meta/control

In addition:
b chord: backspace
d chord: delete
t chord: tab
46 chord: return

Other internals:

2356 chord: rotate BrailleLite by 180 degrees
o chord: set two digit (00-99) repeat count for following command.  Starts
  at 00 (default 01), new digits scroll in from right.  Either terminate
  with e chord, or z chord to cancel, or chorded command.  Works with
  cursor movement as well as keyboard emulation.
