Intermediate, partially working stuff on the 1-sphere.

Chord/SubChord are most probably not the appropriate classes. They are
too complex and should be replaced by something simpler and more
0-dimension, like OrientedPoint in Euclidean 1-D.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1554652 13f79535-47bb-0310-9956-ffa450edef68
Avoid NullPointerException in some corner cases.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1554653 13f79535-47bb-0310-9956-ffa450edef68