use getFOO/setFOO helpers instead of getfield/setfield

use getFOO/setFOO helpers instead of getfield/setfield

Squashed commit of the following:

commit 3ecefd04fb3c2e0dea1764b813ed8840c033d0d0
Author: Hironori Kitagawa <h_kitagawa2001@yahoo.co.jp>
Date:   Tue Aug 16 16:20:02 2022 +0900

    removed trailing spaces

commit c0c3f5dfabdd5148288a5602ebe7caccb3bd2a8b
Author: Hironori Kitagawa <h_kitagawa2001@yahoo.co.jp>
Date:   Sun Aug 14 16:50:55 2022 +0900

    {g/s}etlist whenever possible

commit f9e21bbe9598663f8a19bb4152e65c3f7a6e71b4
Author: Hironori Kitagawa <h_kitagawa2001@yahoo.co.jp>
Date:   Sun Aug 14 14:23:09 2022 +0900

    node.direct.free -> node.direct.flush_node if possible

commit 908d5f6d2e51863129109ed661c4dbaa9b517f9c
Author: Hironori Kitagawa <h_kitagawa2001@yahoo.co.jp>
Date:   Sun Aug 14 07:58:42 2022 +0900

    fix memory leak of  luatexja.jfont.append_italic()

commit 52cce4c3dfc5c9adec707951d8c522bd349a8cb7
Author: Hironori Kitagawa <h_kitagawa2001@yahoo.co.jp>
Date:   Sat Aug 13 18:11:39 2022 +0900

    ltj-direction.lua: format change

commit 2dc75338b41e7f938b6c36ea1d1307aed1263096
Author: Hironori Kitagawa <h_kitagawa2001@yahoo.co.jp>
Date:   Sat Aug 13 11:51:00 2022 +0900

    more getfield(n, FOO) -> getFOO(n)

commit 68c576690e0aa423e3c0dd73d6c30ec9b9ddcb22
Author: Hironori Kitagawa <h_kitagawa2001@yahoo.co.jp>
Date:   Fri Aug 12 22:05:48 2022 +0900

    use {g,s}et{nucleus,sub,sup,shift,penalty,subtype, ...}

commit d49c708434627a038cf20bcb6a2bc8e323fe6109
Author: Hironori Kitagawa <h_kitagawa2001@yahoo.co.jp>
Date:   Fri Aug 12 18:14:16 2022 +0900

    Use helpers: setnext,{g/s}et{lang.kern}

commit ba1a9ceec35115400ff7ab8b1c71d9b7ceff8ee0
Author: Hironori Kitagawa <h_kitagawa2001@yahoo.co.jp>
Date:   Fri Aug 12 05:20:21 2022 +0900

    clear boxes which are unused

commit 43093c57ff8c9df3b891c8ca8b0b9b345cac1af3
Author: Hironori Kitagawa <h_kitagawa2001@yahoo.co.jp>
Date:   Thu Aug 11 16:10:15 2022 +0900

    WIP: unnecessary attribute list