Add gcodeviewer desktop file

Also install it with `make install`

CMakeLists.txt

@@ -514,8 +514,10 @@ elseif (SLIC3R_FHS)
     set(SLIC3R_FHS_RESOURCES "${CMAKE_INSTALL_FULL_DATAROOTDIR}/PrusaSlicer")
     install(DIRECTORY "${SLIC3R_RESOURCES_DIR}/" DESTINATION "${SLIC3R_FHS_RESOURCES}")
     install(FILES src/platform/unix/PrusaSlicer.desktop DESTINATION ${SLIC3R_FHS_RESOURCES}/applications)
+    install(FILES src/platform/unix/PrusaGcodeviewer.desktop DESTINATION ${SLIC3R_FHS_RESOURCES}/applications)
 else ()
     install(FILES src/platform/unix/PrusaSlicer.desktop DESTINATION ${CMAKE_INSTALL_PREFIX}/resources/applications)
+    install(FILES src/platform/unix/PrusaGcodeviewer.desktop DESTINATION ${CMAKE_INSTALL_PREFIX}/resources/applications)
     install(DIRECTORY "${SLIC3R_RESOURCES_DIR}/" DESTINATION "${CMAKE_INSTALL_PREFIX}/resources")
 endif ()
 

src/platform/unix/PrusaGcodeviewer.desktop

@@ -0,0 +1,9 @@
+[Desktop Entry]
+Name=Prusa GCode viewer
+Exec=prusa-slicer --gcodeviewer %F
+Icon=PrusaSlicer # TODO: change when the new icon is ready
+Terminal=false
+Type=Application
+MimeType=text/x.gcode;
+Categories=Graphics;3DGraphics;
+Keywords=3D;Printing;Slicer;