New sphere for ODF reconstruction

Added a new sphere (repulsion724) created from symmetric724 by applying some repulsion iteration (5000).
This sphere is antipodally symmetric and much more evenly distributed, especially at the z=0 equator (see attached image).

Closest points in symmetric724 are 3.70 degrees apart, average distance (to closest neighbor) is 7.08 degrees.
Closest points in repulsion724 are 7.29 degrees apart, average distance (to closest neighbor) is 7.76 degrees.


![sphere_symmetric724_equator_uneveness](https://cloud.githubusercontent.com/assets/2924358/5387533/8cff3ce0-80a9-11e4-9451-204860ad2957.png)