Add icon and desktop entry for vsp executable

Icon is stored in /usr/share/pixmaps/vspIcon.png as a link to
/opt/OpenVSP/vspIcon.png.
Desktop entry file vsp.desktop in /usr/share/applications/ is created by
postinst script.
Both icon and dektop entry files are removed on removal of package.

src/CMakeLists.txt

@@ -127,3 +127,4 @@ INSTALL( DIRECTORY ../examples/scripts/ DESTINATION scripts )
 INSTALL( DIRECTORY ../examples/textures/ DESTINATION textures )
 INSTALL( FILES ../LICENSE DESTINATION . )
 INSTALL( FILES ../README.md DESTINATION . )
+INSTALL( FILES ../vspIcon.png DESTINATION .)

src/cmake/postinst

@@ -6,3 +6,19 @@ ln -nsf /opt/OpenVSP/vspaero /usr/local/bin/vspaero;
 ln -nsf /opt/OpenVSP/vspscript /usr/local/bin/vspscript;
 ln -nsf /opt/OpenVSP/vspslicer /usr/local/bin/vspslicer;
 ln -nsf /opt/OpenVSP/vspviewer /usr/local/bin/vspviewer;
+echo "Setting up desktop entry ...";
+ln -nsf /opt/OpenVSP/vspIcon.png /usr/share/pixmaps/vspIcon.png
+cat >> /usr/share/applications/vsp.desktop <<EOL
+[Desktop Entry]
+Type=Application
+Version=1.0
+Name=OpenVSP
+Comment=Parametric aircraft geometry tool
+Icon=/usr/share/pixmaps/vspIcon.png
+Exec=/usr/local/bin/vsp
+Terminal=false
+Categories=Education;Science;Physics;Engineering;
+Keywords=airfoil;aircraft;model;design;
+EOL
+chmod +x /usr/share/applications/vsp.desktop;
+desktop-file-install /usr/share/applications/vsp.desktop;

src/cmake/postrm

@@ -6,3 +6,6 @@ rm -f /usr/local/bin/vspaero;
 rm -f /usr/local/bin/vspscript;
 rm -f /usr/local/bin/vspslicer;
 rm -f /usr/local/bin/vspviewer;
+echo "Removing desktop entry ...";
+rm -f /usr/share/pixmaps/vspIcon.png
+rm -f /usr/share/applications/vsp.desktop