These variables are set in top.js

in getMolToLoad()

	If there is no "mol=" in the query string, fatal error.

	pdbToLoad is everything between mol= and &, unescaped. Can be full url, code only, code.pdb.

		processHeaderBeforeMolView (boolean) true if pdbToLoad contains e.g. "consurf".

	pdbFilename is the PDB code or a filename at the end of a URL
		(with everything up to the last slash removed).

	pdbId is UPPER CASE filename with ".pdb" trimmed off, if present.

	usePDBId is true if pdbId is a valid PDB code.

	validPDBId
		// Contains a valid PDB Id if pdbToLoad was a valid PDB Id,
		// or if the first four characters of pdbId are a valid PDB Id. Else blank.
		// CONSURF upload: pdbId is "DATA". PDB ID is not in URL.

	pdbURL; // URL Jmol uses to fetch the molecule.

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UPLOADED PDB files end up as DATA.pdb.

When ConSurf, the PDB ID is in FGij javascript consurf_pdb_id (not conveyed to FG).
However we want a more general solution using HEADER.

consurf/msgcall.js: At the end of the header -> processPDBHeader()
  which splits into pipeBlock and pdbHeader
	new in FG 3.8 function getPDBIdFromHeader() extracts the PDB ID from the HEADER line
		if it has not already in validPDBId.