adjust linux install; add desktop file

[LuckyTurtleDev]

before: (usr as DCMAKE_INSTALL_PREFIX)

usr
└── Commander_Wars_Release
    ├── bin
    │   └── Commander_Wars
    ├── lib
    │   └── Commander_Wars
    │       ├── addr2line
    │       └── platforms
    │           ├── libqeglfs.so
    │           ├── libqlinuxfb.so
    │           ├── libqminimalegl.so
    │           ├── libqminimal.so
    │           ├── libqoffscreen.so
    │           ├── libqvnc.so
    │           ├── libqwayland-egl.so
    │           ├── libqwayland-generic.so
    │           └── libqxcb.so
    └── share
        ├── Commander_Wars
        │   └── templates
        │       ├── gamescript.js
        │       └── init.js
        └── pixmaps
            └── Commander_Wars.png
                └── icon.png

after: (usr as DCMAKE_INSTALL_PREFIX)

usr
├── bin
│   └── commander_wars
├── lib
│   └── commander_wars
│       ├── addr2line
│       ├── libqeglfs.so
│       ├── libqlinuxfb.so
│       ├── libqminimalegl.so
│       ├── libqminimal.so
│       ├── libqoffscreen.so
│       ├── libqvnc.so
│       ├── libqwayland-egl.so
│       ├── libqwayland-generic.so
│       └── libqxcb.so
└── share
    ├── applications
    │   └── Commander_Wars.desktop
    ├── commander_wars
    │   └── templates
    │       ├── gamescript.js
    │       └── init.js
    └── pixmaps
        └── commander_wars.png

• fix icon path
• add desktop file for starmenu entry and other desktop integration.
• move sub-sub-folder up at lib (never seen this before, no idea if the linker does check this folder)
• use lowercase for binary. Linux filesystem is case sensitive. (I think Mac and Unix also). Binaries should be lowercase by convention.
• remove Commander_Wars_Release prefix. Can still be used, by using cmake options: -DCMAKE_INSTALL_PREFIX=Commander_Wars_Release

I think addr2line should be removed, because it is not used on Linux, but I have no idea how I can do that.