Revise Linux desktop integration

[richardwilkes]

The current (as of GCS 4.14) integration with the Linux desktop and the install experience is poor under Linux. Consider replacing the Java packager that is being used with something else, perhaps even something as simple as a .tar.gz file again, or a binary that does an install.

Relevant specs that should be used to better integrate with the desktop:

• XDG Base Directory Specification
• Desktop Menu Specification
• Desktop Entry Specification
• Icon Theme Specification

[richardwilkes]

Some other packaging mechanisms:

• Snapcraft
• Flatpak

[richardwilkes]

I've recently experimented with Flatpak. Unfortunately, I had some issues getting it to do what I wanted. It might be better to just ship a binary that wraps the actual GCS distribution and when run, unpacks it onto the target and installs the relevant extra bits in all the relevant system directories. Really a shame that Linux apps can't be self-contained.