change visibility of attributes in Command to protected
move some share methods from Logic(old) to Command
AddCommand extends Command
move some static methods from Logic(old) to Command
markCommand extends Command
UpdateCommand extends Command
DeleteCommand extends Command
ConfirmCommand extends Command
nothing
HelpCommand extends Command
move showhelp()
viewCommand extends Command
SearchCommand extends Command
RedoCommand extends Command
UndoCommand extends Command
ExitCommand extends Command
InvalidCommand extends Command
clear constructors
change dbmanager and startdatabase() to static
start database in RubberDuck class