Make Application into a singleton

Signed-off-by: Slendi <slendi@socopon.com>

src/Application.cpp

@@ -1075,4 +1075,10 @@ auto Application::is_key_released(uint32_t key) const -> bool
 	return !m_key_state[key] && m_key_state_previous[key];
 }
 
+auto Application::the() -> Application &
+{
+	static Application self {};
+	return self;
+}
+
 } // namespace Lunar

src/Application.h

@@ -38,6 +38,8 @@ struct Application {
 	auto is_key_pressed(uint32_t key) const -> bool;
 	auto is_key_released(uint32_t key) const -> bool;
 
+	static auto the() -> Application &;
+
 private:
 	auto init_input() -> void;
 	auto init_test_meshes() -> void;

src/main.cpp

@@ -1,7 +1,3 @@
 #include "src/Application.h"
 
-auto main() -> int
-{
-	Lunar::Application app {};
-	app.run();
-}
+auto main() -> int { Lunar::Application::the().run(); }