Minor code cleanup

src/modules/keyboard/sdl/Keyboard.cpp

@@ -51,12 +51,11 @@ bool Keyboard::hasKeyRepeat() const
 
 bool Keyboard::isDown(Key *keylist) const
 {
-	const Uint8 *keystate = SDL_GetKeyboardState(0);
-	std::map<Key, SDL_Keycode>::const_iterator it;
+	const Uint8 *keystate = SDL_GetKeyboardState(nullptr);
 
 	for (Key key = *keylist; key != KEY_MAX_ENUM; key = *(++keylist))
 	{
-		it = keys.find(key);
+		auto it = keys.find(key);
 		if (it != keys.end() && keystate[SDL_GetScancodeFromKey(it->second)])
 			return true;
 	}

src/modules/keyboard/sdl/Keyboard.h

@@ -56,6 +56,8 @@ public:
 
 private:
 
+	// Whether holding down a key triggers repeated key press events.
+	// The real implementation is in love::event::sdl::Event::Convert.
 	bool key_repeat;
 
 	static std::map<Key, SDL_Keycode> createKeyMap();

src/modules/keyboard/wrap_Keyboard.cpp

@@ -29,7 +29,7 @@ namespace love
 namespace keyboard
 {
 
-static Keyboard *instance = 0;
+static Keyboard *instance = nullptr;
 
 int w_setKeyRepeat(lua_State *L)
 {
@@ -87,7 +87,7 @@ static const luaL_Reg functions[] =
 
 extern "C" int luaopen_love_keyboard(lua_State *L)
 {
-	if (instance == 0)
+	if (instance == nullptr)
 	{
 		EXCEPT_GUARD(instance = new love::keyboard::sdl::Keyboard();)
 	}