Fix vertex ordering for beginShape(QUADS) in WebGL mode

[davepagurek]

Resolves #5770

In my last PR adding QUADS support, I misread the example code in the p5 reference and thought that the vertex ordering for QUADS and QUAD_STRIP were the same, but they are actually supposed to be different. This fixes it and makes QUADS consistent with 2D mode.

Changes:

• Updated the code for adding a QUADS vertex() to use a CCW vertex ordering, consistent with 2D mode
• Updated manual and unit tests to also use that ordering

Screenshots of the change:
Using the example code for QUADS from the p5 reference, but in WebGL mode:

beginShape(QUADS); vertex(30, 20); vertex(30, 75); vertex(50, 75); vertex(50, 20); vertex(65, 20); vertex(65, 75); vertex(85, 75); vertex(85, 20); endShape();	Before:	After:

PR Checklist

• npm run lint passes
• [Unit tests] are included / updated

[stalgiag]

Good catch!

[davepagurek]

Thanks for reviewing this so quickly! Have a great rest of your weekend 🙂