This will allow development of a better terminal providing stdin.
Added new system calls settermmode(2) and gettermmode(2) declared in
<sys/termmode.h>. They allow querying and changing the current mode of
terminals (enabling raw keyboard data, signal handling, line buffering,
UTF-8 encoding stdin, and more). However, all that is unsupported by the
current terminal device driver.
Added KBKEY_ENCODE and KBKEY_DECODE macros to <sys/keycodes.h> which allows
encoding the kbkey format in UTF-32 characters.
