⭐ Add getters to access CarbonPeriod like a DatePeriod object

[kylekatarnls]

I encountered an issue with the following code:

$period = new DatePeriod(...);
var_dump($period->start); // Contains the start date of the period
$period = new CarbonPeriod(...);
var_dump($period->start); // Error: Undefined property

Carbon version: 2.40.0

PHP version: 7.1.8

Actually: CarbonPeriod objects does not have any properties/getters to access the period definition like the DatePeriod can.

Expected: It would be great that as a polyfill CarbonPeriod would have equivalent possibility using a magic getter __get to access:

start
end
interval
recurrences
include_start_date
include_end_date
current