Ballsy! World Cup 2020 v15 update - PS4 controller fix

By compiling with the latest Unity version, a controller issue was fixed.

I also made a little gameplay change: if you accelerate from walk to sprint speed, it would only do so in the direction you were currently moving in. This was a deliberate gameplay choice to force players to have the player change direction first, before they fully accelerated. However, I have changed my mind since, as I feel the downside weighs too heavily: it doesn't feel very intuitive.

If you preferred the old way a lot more, just stick with v14, as it's otherwise the same anyway (unless you had the controller issue)!

If you notice any regressions with this build, let me know!

Full changelog v15:

    - compiled with new unity to fix PS4/DS4Win controller issues
    - can now accelerate to sprint into any direction, rather than only near the current walk direction
    - team 1 (player team) now selected by default on world cup matches, to avoid confusion