Added a time estimation for the transverse curve search.
Now we can draw TransverseCurves, however there are bugs:

1. The generation of SeparatrixSegments in the upwards direction is
wrong. The left- and right-shifted segments should be completely
different, yet their data is the same.

2. There are non-connected curves in the TransverseCurveDatabase.

3. The drawing code of TransverseCurves is also buggy.