Fix Vector2f/d.perpendicular()

[ieperen3039]

the calculation for y used the new value of x

[httpdigest]

Thanks for finding and fixing! Those kind of bugs were all introduced by 50359e9#diff-5f25b65b863f5962b1afa652e0479798L507 (see the Vector2d diff).
Sadly, this was a simple "inline refactor" done via Eclipse, which I assumed would be correct. However it totally screwed things up in this case.

[httpdigest]

Yeah, Eclipse's method invocation inlining refactor (Shift+Alt+I) is to blame. Take for example this simplified case:

public class Vector2f {
  public float x, y;
  public Vector2f perpendicular() {
    return this.set(y, -x);
  }
  private Vector2f set(float x, float y) {
    this.x = x;
    this.y = y;
    return this;
  }
}

and inline the this.set(y, -x) invocation in perpendicular(). The result will be:

public Vector2f perpendicular() {
  this.x = y;
  this.y = -x;
  return this;
}

which is totally wrong here. Apparently, Eclipse's method inline refactor (Eclipse version 2020.03) is broken, not taking into account Java's call-by-value argument passing, necessitating a temporary variable in this case.

[ieperen3039]

I believe IntelliJ does it correctly