Controller support added

As requested I've quickly implemented a basic gamepad / controller input layer.

The entire game should be navigateable from A to Z and completely playable, albeit there are some caveats;

• Hints and tips will still display keyboard / mouse names - I will have to refactor this so I can show actual buttons.. But for this I need more controllers as well.

• Car controls are a bit funky, you'll have to use the joystick instead of trigger buttons to step on the gas.

• The game is much harder with a controller, as there is no aim-assist.

• You can't re-map controls yet (only configure the movement / aim speed) in-game. If you want to edit those, you will have to fiddle with the button numbers in the "settings" file located here: %LOCALAPPDATA%\\ShootMUp\\settings

This file is an INI file that will contain a section of "GP_CONTROLS". The numbers there relate to the numbers you see in the Windows "game controller properties", except that the numbers in the ini-file are 0based (the control window starts counting from 1). So if you want to make some changes, you'll have to check the number in the properties screen, then deduct 1 from it, and use that number in the config file.

I also don't have that many controllers - I have been developing and testing this with a PS4 controller hooked up to my Windows PC, so I hope most controllers will work. You might need to do some remapping - feel free to share re-mapped configs in the discussions! Ofcourse I'm also available on Discord for any burning questions you may have.

Enjoy!!