PICO-8 Standalone - Mouse/Menu key Improvements and fixes in SDL2 lib

[XK9274]

Mouse can be tested in this cart (which is also available through splore): https://www.lexaloffle.com/bbs/?tid=3467

• Fixes menu button handling so it doesn't exit on "PRESSED" event (fixes being unable to screenshot, change brightness etc) (may take 2 presses)
• Fixes mouse bounds from previous regression in #1425

• Adds option flags to onioncfg.json to:

  • Hide the mouse icon
  • Set custom mouse bounds in the config (mostly for testing purposes)
  • Remove the mouse hotkey altogether so it can be rebound to something else

  These values will default to:

  #define MMIYOO_DEFAULT_MOUSE_HOTKEY         0
  #define MMIYOO_DEFAULT_MOUSE_ICON           0
  #define MMIYOO_DEFAULT_MOUSE_MINX           40
  #define MMIYOO_DEFAULT_MOUSE_MINY           0
  #define MMIYOO_DEFAULT_MOUSE_MAXX           280
  #define MMIYOO_DEFAULT_MOUSE_MAXY           236

  If they do not exist in the json config file.

  Which should look like:

  "mouse":{
    "scaleFactor":1,
    "acceleration":4.0,
    "accelerationRate":1.5,
    "maxAcceleration":4.0,
    "incrementModifier":1.0,
    "disableMouseHotkey":0,
    "disableMouseIcon":1,
    "minx":40,
    "miny":0,
    "maxx":280,
    "maxy":236
  },

When:

     "disableMouseHotkey":1,

Is set, L2 can be rebound to a different key with:

  "customkeys":{
    "A":"Z",
    "B":"X",
    "X":"ESCAPE",
    "Y":"D",
    "L1":"D",
    "L2":"D", <<<<<<<<<<
    "R1":"D",
    "R2":"D",
    "LeftDpad":"LEFT",
    "RightDpad":"RIGHT",
    "UpDpad":"UP",
    "DownDpad":"DOWN",
    "Start":"RETURN",
    "Select":"D",
    "Menu":"D"
  },