Add setup script for linux

Installer/setup.sh

@@ -0,0 +1,31 @@
+#!/bin/sh
+set -eu
+
+if [ "$(id -u)" -ne 0 ]; then
+    echo 'root privileges required' >&2
+    exit 1
+fi
+
+copy_sl_config() {
+	if [ -e "/opt/itgmania/Themes/Simply Love.old/$1" ]; then
+		cp "/opt/itgmania/Themes/Simply Love.old/$1" "/opt/itgmania/Themes/Simply Love/$1"
+	fi
+}
+
+cd "$(dirname "$0")"
+
+# Move the old SL release out of the way
+[ -d /opt/itgmania/Themes/Simply\ Love ] && mv /opt/itgmania/Themes/Simply\ Love{,.old}
+
+# Install ITGm
+[ -d /opt ] || install -d -m 755 -o root -g root /opt
+cp -R --preserve=mode,timestamps itgmania /opt
+ln -sf /opt/itgmania/itgmania.desktop /usr/share/applications
+
+# Copy persistent files over from the old SL folder
+if [ -d /opt/itgmania/Themes/Simply\ Love.old ]; then
+	copy_sl_config Other/SongManager\ PreferredCourses.txt
+	copy_sl_config Other/SongManager\ PreferredSongs.txt
+
+	rm -rf /opt/itgmania/Themes/Simply\ Love.old
+fi

itgmania.desktop

@@ -1,10 +1,10 @@
 [Desktop Entry]
 Name=ITGmania
 GenericName=Rhythm and dance game
-TryExec=/usr/local/itgmania/itgmania
-Exec=/usr/local/itgmania/itgmania
+TryExec=/opt/itgmania/itgmania
+Exec=/opt/itgmania/itgmania
 Terminal=false
-Icon=/usr/local/itgmania/Data/icon.png
+Icon=/opt/itgmania/Data/icon.png
 Type=Application
 Categories=Game;ArcadeGame
 Comment=A cross-platform rhythm video game.

src/CMakeLists.txt

@@ -507,6 +507,11 @@ if(WIN32)
           DESTINATION "${SM_FULL_INSTALLATION_PATH}")
 else()
   install(TARGETS "${SM_EXE_NAME}" DESTINATION "${SM_INSTALL_DESTINATION}")
+  if(LINUX)
+    install(FILES "${SM_ROOT_DIR}/itgmania.desktop"
+            DESTINATION "${SM_INSTALL_DESTINATION}")
+    install(PROGRAMS "${SM_ROOT_DIR}/Installer/setup.sh" DESTINATION ".")
+  endif()
 endif()
 install(DIRECTORY "${SM_ROOT_DIR}/Announcers"
         DESTINATION "${SM_INSTALL_DESTINATION}")