code: protected void generalHelp(AsciiTable at){
  		//collect all commands belonging to a particular category
  		String defKey = "__standard";
  		Map<String, TreeMap<String, SkbShellCommand>> cat2Cmd = new TreeMap<>();
  		for(CommandInterpreter ci : this.skbShell.getCommandMap().values()){
  			for(SkbShellCommand ssc : ci.getCommands().values()){
  				String cat = defKey;
  				if(ssc.getCategory()!=null){
  					cat = ssc.getCategory().getCategory();
  				}
  				if(!cat2Cmd.containsKey(cat)){
  					cat2Cmd.put(cat, new TreeMap<>());
  				}
  				cat2Cmd.get(cat).put(ssc.getCommand(), ssc);
  			}
  		}
  
  		//no argument, means general help
  		at.addRow(null, this.skbShell.getDisplayName() + "-" + this.skbShell.getDescription());
  		at.addRule();
  
  		//do the commands per category, starting with "__standard"
  		for(String cat : cat2Cmd.keySet()){
  			String catDescr = cat;
  			if(defKey.equals(cat)){
  				catDescr = "standard commands";
  			}
  			at.addRow(catDescr, new StrBuilder().appendWithSeparators(cat2Cmd.get(cat).keySet(), ", "));
  			at.addRule();
  		}
  		at.addRow(null, "try: 'help <command>' for more details");
  	}
docs: Processes general help with no specific command requested.
  @param at table to add help information to