First implementation of Electromagnetic pusher.
Some testing is still required.
Documentation needs to be upgraded to match the changes in this branch.
A new option has been added in which MCC are computed with its own time
step.
If no time is provided, then the minimum time step of the simulation is
employed.
Fixed an issue in which the position in triangular an thetrahedron
elements were not correctly being computed.
Other minor issues fixed:
- Units in input file now do not use '/'.
- Collisions accuratly conserve momentum.
- Minor improvements in mass calculation in collisions.
An initial simulation time can be provided in the input file. This is
useful when restarting a simulation from a previous file. If no
initial time is provided, the value 0 is used.
