Extremes of drawn ellipses not being calculated correctly.

[DavidACosgrove]

Describe the bug
The ellipse extremes aren't being calculated correctly, such that they may be cutoff by the sides of the drawing.

To Reproduce

  std::string nameBase = "test_github5944";
  auto m = "c1ccccn1"_smiles;
  TEST_ASSERT(m);
  RDDepict::compute2DCoords(*m);
  std::vector<int> highlight_atoms{0, 1, 2, 3, 4, 5};
  MolDraw2DSVG drawer(400, 400);
  drawer.drawOptions().highlightRadius = 1.0;
  drawer.drawMolecule(*m, &highlight_atoms);
  drawer.finishDrawing();
  std::string text = drawer.getDrawingText();
  std::ofstream outs(nameBase + ".svg");
  outs << text;
  outs.flush();
  outs.close();```
**Expected behavior**
A clear and concise description of what you expected to happen.

Screenshots

Configuration (please complete the following information):

• RDKit version: master, built from scratch
• OS: macOS 12.6.2

Additional context
Fix incoming.