Add the velocity_rescale() for rescaling velocities during equilibration.
Implement radial distribution function. The basic MD simulation procedure is done.
Implement the LJ force calculation.
The xcmd_object is updated.  io_read_input() is tested.
Add three FILE pointers for output positions, forces and velocities.
Add functions for converting reduced units to SI units.
Position, force and velocity output stream are created.
Add functions for outputting velocities, forces and coordinates.
Add function for computing current kinetic energy.
Add isFileExists().
Change the energy scale from 0.01 eV to 1 eV.
The basic MD algorithm is implemented but still needs debugging. Anderson thermostat is the next target to implement.
Project update.
Merge pull request #2 from Bismarrck/dev

Dev