The constructor Dislocation(Vector3d burgers, Vector3d line, Vector3d
position, CoordinateSystem *base, double bm, bool m) was converting
Burgers vector and line vectors to the dislocation local co-ordinate
system. This is not necessary as the line vector is always the z-axis of
the dislocation system and the Burgers vector is expressed in the slip-
perform this conversion so it would result in an inconsistency.
Modified Dislocation class documentation to specify that the Burgers
vector and line vector are expressed in the slip-plane co-ordinate
system.