The class 'Configuration' is now called 'RigidBodyMotion', and can be parametrized by the space dimension

[[Imported from SVN: r4003]]

renaming the file 'configuration.hh' to 'rigidbodymotion.hh', which is a lot more meaningful.  Renaming the actual class will follow in a second.

[[Imported from SVN: r4002]]

[[Imported from SVN: r3488]]

[[Imported from SVN: r905]]

[[Imported from SVN: r737]]