Jetbooking: Add option for booking fixed booking intervals/range

[Marcy376]

A new feature to make it possible for jetbooking products and woo products to have a fixed interval/range to be booked, set for a specific number of days only.

At the moment, the booking products can be booked on a daily interval. There is the option to set min and max days but no option for set number of days.

The new feature would allow set intervals to be booked opening the plugin to be used for more types of rental products.

For example, it would be ideal to make a booking product bookable for only 4 days, or only 8 days and have a price set for each package, so when the datepicker is opened only options available for selection from startdate are 4 or 8 days.

An example of this is possible using this pluging, and you can see it in action in this product example.