Fix camera updates being toggled by N key in release mode (#2762)

Author: kahrl

src/defaultsettings.cpp

@@ -58,7 +58,7 @@ void set_default_settings(Settings *settings)
 #if DEBUG
 			"KEY_F4");
 #else
-			"none");
+			"");
 #endif
 	settings->setDefault("keymap_toggle_debug", "KEY_F5");
 	settings->setDefault("keymap_toggle_profiler", "KEY_F6");

src/keycode.cpp

@@ -256,7 +256,11 @@ KeyPress::KeyPress() :
 
 KeyPress::KeyPress(const char *name)
 {
-	if (strlen(name) > 4) {
+	if (name[0] == 0) {
+		Key = irr::KEY_KEY_CODES_COUNT;
+		Char = L'\0';
+		return;
+	} else if (strlen(name) > 4) {
 		try {
 			Key = keyname_to_keycode(name);
 			m_name = name;