[FEATURE] Include SIS inside the AppImage #109
Description
AppImages are supposed to be self-contained, meaning that all the dependencies of the application must be inside the AppImage itself.
Since SIS uses hardcoded paths to retrieve files from the /usr/local/share/sis folder, I have decided that having two copies of SIS (one inside the AppImage and one outside to allow the first one to access the share directory) doesn't make any sense and so I've choosen to keep SIS out of the AppImage and ask the user to install it separately.
I've decided to do that because, even if the AppImage is not self-contained, the AppImage still holds value since it allows the user to update the application (thanks to AppImageUpdate) making it a valid alternative to the snapcraft release.
If we decide to use proot for the Flatpak release (related issue), it can also be embedded inside the AppImage to allow SIS to be distributed together with betterSIS.