…iable substitution. The substituted variables are enclosed in @ symbols. The script is then run when building so long as -DPACKAGE_NIX was passed to the configure step of cmake and install was specified when building. See https://github.com/bluescan/tacentview/wiki/Distributing

…et data. Disabled the CMake NIX script as it's not needed.

…by packaging/installing the deb build. Extension isn't necessary since the icons are in a standard search directory.

…our-indexed png files with transparency. Fetching a version of the tacent library that has the fix for these types of pngs. Pixel format now displayed correctly in the details overlay.

…G data-dirs for the location of the required static assets.

…-portable builds use XDG on Linux.

…rts the data home as /usr/share/, the viewer assets are looked for in /usr/share/tacentview/Assets/

…r development we now use PACKAGE_DEV which basically means the portable file layout but no archive generated. For all package types the About dialog will display what package type was used (Portable ZIP, Portable TGZ, Snap, Deb, Nix, or Dev).

…se, this shell script was missed by the last commit.