Add scene::on_text_input event

libs/app/include/psemek/app/scene.hpp

@@ -35,6 +35,8 @@ namespace psemek::app
 		virtual void on_key_down(SDL_Keycode /* key */) {}
 		virtual void on_key_up(SDL_Keycode /* key */) {}
 
+		virtual void on_text_input(std::string_view /* text */) {}
+
 		virtual void update() {}
 		virtual void present() {}
 	};

libs/app/source/app.cpp

@@ -209,6 +209,9 @@ namespace psemek::app
 		case SDL_KEYUP:
 			handler()->on_key_up(e.key.keysym.sym);
 			break;
+		case SDL_TEXTINPUT:
+			handler()->on_text_input(e.text.text);
+			break;
 		}
 	}