Sketch solver does not converge Angle constraint with bad starting point

Example of "bad" or problematic starting point:

```
.segment((0, 0), (1.0, 0), "seg1")
.segment((0, 0), (-1.0, 0.0), "seg2")
.constrain("seg1", "seg2", "Angle", 30)
```

Another example with segment-arc when tangents are opposite:
```
.segment((-0.5, -2), (-0.5, 0.0), "seg1")
.arc((-0.5, 0.0), (0.0, -0.5), (0.5, 0.0), "arc1")
.constrain("seg1", "arc1", "Coincident", None)
.constrain("seg1", "arc1", "Angle", 30)
```

Starting point before solve:

I'm testing a fix for this issue by checking if the tangent vectors are opposite, then rotating one of the vectors to push the optimizer in one direction (maybe need to check parallel for other cases):
```
if v1.IsOpposite(v2,TOL/2):
v1 = v1.Rotated(TOL)
```

So far this appears to be working in my testing.