Add key entries for Eisu_toggle and Muhenkan

[tom-tan]

This request adds key type entries for Eisu_toggle and Muhenkan, which are used in Japanese keyboards for macOS and Windows computers.
It also adds missing entry of kKeyNameMap for kKeyKana.

These keys are important for Japanese input methods that input Japanese characters from alphabets (e.g., "ひらがな" from "hiragana").

• Henkan and Muhenkan are used to enable and disable input methods, respectively in Windows computers.
  • Henkan is already available in key_types.h and key_types.cpp
• Kana and Eisu_toggle are used to enable and disable input methods, respectively in macOS computers.
  • Kana is already available in key_types.h but not available in key_types.cpp

This request makes easier for Japanese users to share a keyboard between Windows and macOS computers while keeping the functionality of Japanese input methods.

Note: I searched for keysyms for Eisu_toggle and Muhenkan in the following link: http://wiki.linuxquestions.org/wiki/List_of_Keysyms_Recognised_by_Xmodmap.

[shymega]

Looks sane to me, approving, but going to ask @p12tic to review as well.

[shymega]

Looks sane to me - and CI has passed, so happy to merge 👍

[tom-tan]

ping!

[p12tic]

@tom-tan Many thanks for the pull request!

[amosbird]

Hmm, I've built the latest master but still cannot have Eisu_toggle mapping in

[tom-tan]

As I mentioned in #832, it needs extra work to work these keys in GUI editor.
You can add keystroke settings by editing configuration file directly.

See also: #840.