Fit to Plan 9's ANSI/POSIX compatibility layer

Fit to Plan 9's ANSI/POSIX compatibility layer

tr(1) of ANSI/POSIX environment, aka APE, don't support \n literal.
It's handles only octal(\ooo) or hexadecimal(\xhhhh) numbers.

And its sed(1)'s label is limited to maximum seven characters.
Therefore I replaced some labels to drop a character.

* close -> cl
* continue -> cont (cnt is used for count)
* line -> ln
* hered -> hdoc
* shell -> sh
* string -> str

Signed-off-by: Kyohei Kadota <redacted>
Signed-off-by: Junio C Hamano <redacted>