Add creation of icons for .desktop file

[joede]

The GUI doesn't provide the icons needed to work with the .desktop file. See #684! With this PR, I've added a script to create the necessary hicolor icons from the given SVG file.

I'm no CMake user, so I don't know how to add the .desktop and the icons to CMakelist.txt. After the installation is added to the CMakelist.txt, the debian/stlink-gui.install must be patched too.

This is still needed:

• copy stlink.desktop as stlink-gui.desktp to /usr/share/applications/ (${CMAKE_INSTALL_DATADIR}/applications/?)
• copy stlink-gui.xpm to /usr/share/pixmaps/
• copy hicolor/* to /usr/share/icons/hicolor/
• copy stlink-gui_icon.svg to /usr/share/icons/hicolor/scalable/stlink-gui.svg

[xor-gate]

Maybe @Vascom can help you out with this?

[Vascom]

As I found it is enough have only svg file.

[xor-gate]

This PR has been catching dust, @joede could you verify svg is enough?

[joede]

@xor-gate I can try it within the next days. I expect that GNOME should work with this, but I can't say which other desktops needs images. So I only can test the icon usage with GNOME3!

[joede]

OK, the icon is visible in GNOME3.

I've updated to PR to install the .desktop and the SVG icon with the Debian package. Therefore I have renamed the two files to stlink-gui.* which is IMO better. I have removed the installation instructions from the main CMakeList.txt to the CMakeList.txt of the stlink-gui one. Now all GUI related action is inside this file and no longer spread over two files.

Again: I don't know if the images are necessary for other desktops! Not all desktops use SVG...

[Vascom]

I suggest leaving only SVG and keeping track of bug reports.

[xor-gate]

@Vascom agreed

[xor-gate]

Thanks @joede for your contribution.