HEDTU - ἡ ἐκτεταμένη διάταξις τοῦ Unicode
The extended unicode keyboard layout
The standard layout lacks important symbols, particularly math-related ones and has very arbitrary allocation of certain special characters, such as ?!/\ and this layout is a simple solution
sudo ./HEDTU [language] [format] <options>
Currently available languages: eng, ell, isv, pol
Layouts: QWERTY, Dvorak, JCUKEN
Formats: xkb, fcitx5