Removed Class DetectorSector and created class DetectorSectors that contains 6 faces, one for each sector and has a method getHitSector(Line3D) which returns the index of the sector intersected by the line, otherwise 0.  This was to reduce the amount of redundant code shared between CLASEDetector and CLASFTOFDetector.

Modified the constructors of DetectorPaddle to make DetectorPaddle safe to extend.  Added methods intersect and intersectFront to reduce the amount of redundant code.

Modifed CLASFTOFDetector to make use of new functions changes to DetectorPaddle and DetectorSectors.
Merge branch 'master' of https://github.com/gavalian/clas-geometry