fix camera slerp() BUG

[inaridarkfox4231]

fix column() to row().

Resolves #6508

Changes:

A bug occurred in camera's slerp() due to a change in the specifications of column() and row().
So I'll fix that.

CAMERA_SLERP_BUG

before

  // BUG IS HERE.

  var front0 = rotMat0.column(2);
  var front1 = rotMat1.column(2);
  var up0 = rotMat0.column(1);
  var up1 = rotMat1.column(1);

after

  // The specifications of column() and row() have been reversed, so column() must be rewritten as row().
  var front0 = rotMat0.row(2);
  var front1 = rotMat1.row(2);
  var up0 = rotMat0.row(1);
  var up1 = rotMat1.row(1); // prepare new vectors.

PR Checklist

• npm run lint passes
• Inline documentation is included / updated
• Unit tests are included / updated

[inaridarkfox4231]

Since the unit test did not detect this bug, we will add one unit test to prevent this from happening in the future.

[inaridarkfox4231]

That's all.

[inaridarkfox4231]

I thought that for some reason there was a mismatch regarding line breaks, but it seems I was mistaken.

[davepagurek]

Thanks for the fix + the test case for preventing future regressions!