It now uses SQP for problems without inequality constraints, which is
faster.
main:
```
[ RUN ] Ellipse2dTest.DistanceToPoint
0.203 ms
[ OK ] Ellipse2dTest.DistanceToPoint (0 ms)
[ RUN ] Ellipse2dTest.FindNearestPoint
0.019 ms
[ OK ] Ellipse2dTest.FindNearestPoint (0 ms)
```
upgrade:
```
[ RUN ] Ellipse2dTest.DistanceToPoint
0.197 ms
[ OK ] Ellipse2dTest.DistanceToPoint (0 ms)
[ RUN ] Ellipse2dTest.FindNearestPoint
0.015 ms
[ OK ] Ellipse2dTest.FindNearestPoint (0 ms)
```
