Preserve nightly rate applied from OwnerREz on a per-booking basis

Seems like this would be an easy thing to implement for those users who control rates from OwnerRez.

And knowing that this would happen would help prevent users (like me) from tweaking rates in an OTA platform rather than adjusting from within OR such as with the Rate Calendar.

Implementation
- at booking time determine the calculated nightly rate and record it for each booked night
- add an exportable report to allow users after the fact to easily list all booked nightly rates and associated daily details (such as min nites)
- bonus points for revealing past nightly rates through hover in the Rate Calendar *

* possibly with a calendar display, but in any case where the past year rate is adjusted to match the current year day (eg: mondays match mondays)