function splitIntoPres( preBlock )
	{
		// Exclude the ones at header OR at tail,
		// and ignore bookmark content between them.
		var duoBrRegex = /(\S\s*)\n(?:\s|(<span[^>]+_fck_bookmark.*?\/span>))*\n(?!$)/gi,
			blockName = preBlock.getName(),
			splitedHtml = replace( preBlock.getOuterHtml(),
				duoBrRegex,
				function( match, charBefore, bookmark )
				{
				  return charBefore + '</pre>' + bookmark + '<pre>';
				} );

		var pres = [];
		splitedHtml.replace( /<pre>([\s\S]*?)<\/pre>/gi, function( match, preContent ){
			pres.push( preContent );
		} );
		return pres;
	}
Split into multiple <pre> blocks separated by double line-break.
@param preBlock