lagrangian: Corrected patch data

The KinematicCloud::patchData method has been made consistent on moving
meshes and/or when the time-step is being sub-cycled.

It has also been altered to calculate the normal component of a moving
patch's velocity directly from the point motions. This prevents an
infinite loop occuring due to inconsistency between the velocity used to
calculate a rebound and that used when tracking.

Some minor style improvements to the particle class have also been made.