chore(install): rename .desktop and .appdata.xml

The xdg-desktop specification strongly recommends to use a reverse
domain name, so follow that.

cmake/Installation.cmake

@@ -32,9 +32,11 @@ if(APPLE)
   " COMPONENT Runtime
   )
 else()
-  install(TARGETS ${PROJECT_NAME} RUNTIME DESTINATION "bin")
-  install(FILES "res/qTox.appdata.xml" DESTINATION "share/metainfo")
-  install(FILES "qtox.desktop" DESTINATION "share/applications")
+  include( GNUInstallDirs )
+  # follow the xdg-desktop specification
+  install(TARGETS ${PROJECT_NAME} RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}")
+  install(FILES "res/io.github.qtox.qTox.appdata.xml" DESTINATION "${CMAKE_INSTALL_DATAROOTDIR}/metainfo")
+  install(FILES "io.github.qtox.qTox.desktop" DESTINATION "${CMAKE_INSTALL_DATAROOTDIR}/applications")
 
   # Install application icons according to the XDG spec
   set(ICON_SIZES 14 16 22 24 32 36 48 64 72 96 128 192 256 512)

res/io.github.qtox.qTox.appdata.xml

@@ -1,7 +1,8 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!-- Copyleft 2016 SkyzohKey <skyzohkey@framasphere.org> -->
 <component type="desktop">
- <id>qtox.desktop</id>
+ <id>io.github.qtox.qTox</id>
+ <launchable type="desktop-id">io.github.qtox.qTox.desktop</launchable>
  <metadata_license>CC-BY-SA-3.0</metadata_license>
  <project_license>GPL-3.0</project_license>
  <name>qTox</name>