v0.0.7

add .vsd support (Gromacs virtual site definition)

v0.0.6

Finished most common file formats:

• NAMD: rtf, pdb, prm, psf, str, inp
• Amber: in, prmtop, inpcrd, prepin, frcmod, lib/off, ac, mc
• Gromacs: gro, atp, arn, rtp, hdb, r2b, tdb, mtp (pmx), ...
• small molecule: sdf, mol2 (modified from gromacs helper), ...
• PLUMED: .plumed.dat