makeBgBlack/WhiteSpt() top.js in scripts.js does bkg and fixes bkg for all echos & scale!

makeEchoPdbIdSpt(""); // blank parameter means get color from toggle

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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.
	It is displayed in JSmol top left. "_CONSURF" is added for consurf results (msgcall.js).
	It can also be the first 10 characters of the filename when no PDB ID.
	It is also the TITLE of the browser window.

	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.