request: make .desktop and icon optional

[mcandre]

Command Line Interface (CLI) applications tend to interact poorly with desktop icons. In other words, launching (with no arguments), and usually crashing.

There shouldn't be a desktop icon for most CLI applications.

Can we please make the .desktop file optional for appimagetool? Its validation is overly strict.

Likewise, icons should be optional.

For GUI apps, appimagetool would do well to supply fallback icons, in the event that a .desktop file blanks this field, omits this field, or the AppDir lacks .desktop configuration file.

[TheAssassin]

The icon requirement comes from the historic AppDir specification which we extended for AppImage. Therefore, it cannot be optional.

A .desktop entry is definitely required for CLI tools as well. Many CLI tools have them.