Do some preparation for touch config screen

settings.lua

@@ -8,10 +8,16 @@ local _defaultSettings = {
     fullscreen = false,
     music = true,
 
+    ---@class input
+    ---@field keys table <string, string>
+    ---@field joysticks table <string, string>
+    ---@field mobile table <string, string>
     input = {
         keys = {},
+        joysticks = {},
         mobile = {    -- Should not be changed for any reason, used for mobile only
             enter = 'menu_decide',
+            acback = 'menu_back',
             f13 = 'up',
             f14 = 'down',
             f15 = 'left',