use valid r-DNS application ID

The Freedesktop.org desktop entry specification
recommends an ID "controlled by the author", while the
AppStream specification makes it a requirement.

The desktop entry uses JFileSync3, and the project
internally jfs as inherited from JFileSync. Both are not
registered TLDs.

io.github.mgoellnitz.JFileSync3 is used as it is
guaranteed to be a valid ID through existence of this
repo.

Link: https://specifications.freedesktop.org/desktop-entry-spec/latest/file-naming.html
Link: https://www.freedesktop.org/software/appstream/docs/chap-Metadata.html

Signed-off-by: Markus Göllnitz <camelcasenick@bewares.it>

Author: camelCaseNick

README.md

@@ -118,7 +118,7 @@ You can start the application through
 - a Windows launcher ('JFileSync3.exe')
 - a batch file ('bin/JFileSync3.bat')
 - a Unix shell script ('bin/JFileSync3')
-- a XDG launcher script ('share/applications/JFileSync3.desktop')
+- a XDG launcher script ('share/applications/io.github.mgoellnitz.JFileSync3.desktop')
 
 The XDG launcher script can be automatically modified to reflect the current
 path with the script `share/prepare_xdg_file.sh`.

xdg/applications/JFileSync3.desktop …/io.github.mgoellnitz.JFileSync3.desktopxdg/applications/JFileSync3.desktop renamed to xdg/applications/io.github.mgoellnitz.JFileSync3.desktop xdg/applications/JFileSync3.desktop renamed to xdg/applications/io.github.mgoellnitz.JFileSync3.desktop

@@ -3,7 +3,7 @@ Encoding=UTF-8
 Name=JFileSync3 - 3.0-SNAPSHOT
 Comment=Syncing and Encryption
 Exec=JFileSync3
-Icon=JFileSync3
+Icon=io.github.mgoellnitz.JFileSync3
 Categories=Application;Java
 Version=1.0
 Type=Application

…/icons/hicolor/64x64/apps/JFileSync3.png …apps/io.github.mgoellnitz.JFileSync3.pngxdg/icons/hicolor/64x64/apps/JFileSync3.png renamed to xdg/icons/hicolor/64x64/apps/io.github.mgoellnitz.JFileSync3.png xdg/icons/hicolor/64x64/apps/JFileSync3.png renamed to xdg/icons/hicolor/64x64/apps/io.github.mgoellnitz.JFileSync3.png

@@ -12,7 +12,7 @@ if [ -f $DIR/../lib/JFileSync3.jar ] ; then
     fi
   fi
   PATTERN=$(echo $DIR|sed -e 's/\//\\\//g')\\/
-  sed -i.bak -e "s/^Exec=.*/Exec=${PATTERN}\\/bin\\/JFileSync3/" $DIR/share/applications/JFileSync3.desktop
-  sed -i.bak -e "s/^Icon=.*/Icon=${PATTERN}\\/share\\/icons\\/hicolor\\/64x64\\/apps\\/JFileSync3.png/" $DIR/share/applications/JFileSync3.desktop
+  sed -i.bak -e "s/^Exec=.*/Exec=${PATTERN}\\/bin\\/JFileSync3/" $DIR/share/applications/io.github.mgoellnitz.JFileSync3.desktop
+  sed -i.bak -e "s/^Icon=.*/Icon=${PATTERN}\\/share\\/icons\\/hicolor\\/64x64\\/apps\\/io.github.mgoellnitz.JFileSync3.png/" $DIR/share/applications/io.github.mgoellnitz.JFileSync3.desktop
   rm $DIR/JFileSync3.desktop.bak
 fi