RSCB-PDB web lookups

Relevant links:

Methods not documented here are either private or will be soon, please note the API is not yet stable.

pdb2ref(pdb[, url, timeout])

Print the primary citation of a pdb code via web lookup

pdb2traj(code[, filename, verbose, url])

Return a Trajectory from a four-letter PDB code via RSCB PBB lookup