FET full changelog

The sources and the GNU/Linux binaries are now archived with tar.xz (suggested by Michael Towers).
It is now possible (and recommended) to build FET with CMake (minimum Qt version for CMake: 6.10) (suggested by Michael Towers, who also provided extensive instructions/help on how to do this; also Volker Dirr, assisted by ChatGPT and Gemini, suggested some important corrections). On this occasion, we added an improvement so that the engine is no longer compiled twice, but only once, as a static library (suggested by Volker Dirr, assisted by Gemini). QMake is still supported, but not recommended (one reason is that the engine is compiled twice, and another reason is that it is an old building method). Older Qt versions (5.15 to 6.9) are supported only with QMake. Chichi Lalescu suggested the code to make the conditional building of FET with the language preselected to the local language, enabling the option USE_SYSTEM_LOCALE.
Minor improvements (suggested by Michael Towers, found using Qt Creator).

Improved the command line generation, by removing the additional thread which was checking for the possible existence of the 'sigwrite' file. The new check for the existence of this file is done in the already existing generation thread (idea and code suggested by Michael Chourdakis).
Minor improvement: the History states will now be stored in four std::deque-s instead of four std::list-s (but the improvement is not noticeable in practice).
Minor improvements.

Bug fix in the new feature, introduced in version 7.6.0, to view/edit the related constraints in the timetable view days vertical dialogs (reported by GUEFFAZ REDA).
Improved the layout of the option to view/edit the related constraints from the timetable view dialogs, to save space (suggested by GUEFFAZ REDA).
Corrected the Arabic translation, by Benahmed Abdelkrim (fixing an error reported by GUEFFAZ REDA).

Bug fix in the new feature, introduced in version 7.6.0, to view/edit the related constraints in the timetable view days vertical dialogs (reported by GUEFFAZ REDA).
Improved the layout of the option to view/edit the related constraints from the timetable view dialogs, to save space (suggested by GUEFFAZ REDA).
Corrected the Arabic translation, by Benahmed Abdelkrim (fixing an error reported by GUEFFAZ REDA).

Minor bug fixes (reported by Volker Dirr, found using Cppcheck).
Minor bug fix when printing the advanced statistics.
Minor bug fix: the examples directory contained a special character, which gave warnings on some systems (reported by Andrea Primiani). On this occasion, some other example files were renamed, to avoid the special '+' character in a filename, which is not recommended on older systems.
Code improvements.
Updated the Italian translation, by Andrea Primiani.
Updated the Arabic translation, by Benahmed Abdelkrim.

Bug fixes: when viewing the detailed description of an activity tag in the activity tags dialog, some types of related constraints were not listed.
Code improvements.

Added the option to view/edit the time/space constraints associated with one or more teachers/students sets/rooms/activities, from the timetable view dialogs (suggested by Vangelis Karafillidis, and maybe by other users in the past).

Updated to Qt 6.10.1.

Crash bugs fixed, when using one or more constraints of type teacher(s)/students (set) max mornings/afternoons per week (in the Mornings/Afternoons mode) with the max allowed mornings/afternoons per week set to zero (reported by Thái Chí Phuong).
Corrected a field in the Arabic translation, by Benahmed Abdelkrim.

An English field correction (reported by Vangelis Karafillidis).
Updated the Greek translation, by Vangelis Karafillidis.