Regtest for ves_md_linearexpansion with shifted periodic potential

regtest/ves/rt-md_le-1d-fourier-shifted/Makefile

...est/ves/rt-md_le-1d-fourier-shifted/colvar.data.reference

regtest/ves/rt-md_le-1d-fourier-shifted/config

.../ves/rt-md_le-1d-fourier-shifted/histogram.data.reference

regtest/ves/rt-md_le-1d-fourier-shifted/input

regtest/ves/rt-md_le-1d-fourier-shifted/plumed.dat

...est/ves/rt-md_le-1d-fourier-shifted/pot_coeffs_input.data

...md_le-1d-fourier-shifted/pot_coeffs_output.data.reference

.../ves/rt-md_le-1d-fourier-shifted/potential.data.reference