use Container to get Property; tested getting validation&selector info.
made comments a little easier to read.
added a isRequired and tested it. changed a bit of definition of validation.
probably not to return anything from delete.
try to change things like definition's defs.
removed unused methods to make refactoring easier.
maybe put label as properties' label.
moved under Property to autoload classes.
PropertyCsv to support csv type input.
removed unused method.