* If bytes are still queued after processing as many keypresses as
possible, send a DSR to the console. The console should respond with
a DSR reply, which will flush out the input buffer without having to
wait for a timeout.
* Add ah hoc code for ALT-<character> rather than listing every character
in the table.
* When keypresses have Alt/Ctrl/Shift modifiers, generate extra
INPUT_RECORDS to press and release each modifier. EDIT.COM seemed to
require these for some Ctrl-<key> keypresses I tried.
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