Use 7-Zip instead of p7zip in Linux installation scripts

[Schweineschwarte]

Hello,
since some years, p7zip had no new development. The latest version is from 2016.
Latest version of p7zip
Some Linux distribution do not support p7zip anymore, like openSUSE Leap 16.0.
No support for openSUSE Leap 16.0
Furthermore, 7-Zip has official builds for Linux now.
Direct link to 7-Zip file for Linux x64
7-Zip releases on Github
Please change the dependency of the unpackage program in your Linux installation scripts (like ut99-installer.sh or unrealgold-installer.sh)! Thank you very much :)

[MFG38]

p7zip has been effectively replaced with 7zip in the Arch Linux repositories at the very least - trying to install p7zip will just install 7zip instead.

[Schweineschwarte]

@MFG38 I think they are working on this issue. See: changes to Linux installers

[FineWolf]

We are indeed in the process of rewriting the Linux installation scripts. There is an open PR if you wish to test the new ones.

#19

Note however that the .desktop files will not work until the PR has been merged.

The new installers will not attempt to install the dependencies directly, but will advise the user what to install if the installer detects that it is missing a core dependency.

[FineWolf]

@stijn-volckaert This can most likely be marked as Closed/Resolved with the new installers