Add GUI application installer

[richbl]

DOES

Currently, in order to install the application after it's been compiled/built, there are three steps needed to be done: copy the binary executable; copy the icon file, and copy the .desktop file.

SHOULD

An application installer should be built that does all of this for me. But, should it be written to handle both use cases: user-level installation and system-level installation?

Also... what about creating a Flatpak (consider feasibility first)?