Add cmake config files

CMakeLists.txt

@@ -1,5 +1,5 @@
 cmake_minimum_required (VERSION 3.2.0)
-project (DiscordRPC)
+project (DiscordRPC VERSION 3.4.0)
 
 include(GNUInstallDirs)
 

cmake/Config.cmake.in

@@ -0,0 +1,3 @@
+@PACKAGE_INIT@
+
+include("${CMAKE_CURRENT_LIST_DIR}/@PROJECT_NAME@Targets.cmake")

src/CMakeLists.txt

@@ -128,7 +128,7 @@ endif(CLANG_FORMAT_CMD)
 
 install(
     TARGETS discord-rpc
-    EXPORT "discord-rpc"
+    EXPORT "${PROJECT_NAME}Targets"
     RUNTIME
         DESTINATION "${CMAKE_INSTALL_BINDIR}"
     LIBRARY
@@ -139,9 +139,35 @@ install(
         DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
 )
 
+install(
+    EXPORT "${PROJECT_NAME}Targets"
+    DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"
+    NAMESPACE "${PROJECT_NAME}::"
+)
+
 install(
     FILES
         "../include/discord_rpc.h"
 		"../include/discord_register.h"
     DESTINATION "include"
 )
+
+include(CMakePackageConfigHelpers)
+
+configure_package_config_file("../cmake/Config.cmake.in"
+    "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}Config.cmake"
+    INSTALL_DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"
+)
+
+write_basic_package_version_file(
+    "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake"
+    COMPATIBILITY SameMajorVersion
+)
+
+install(
+    FILES
+        "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}Config.cmake"
+        "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake"
+    DESTINATION
+        "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"
+)