`STNumber` lets objects and transactions contain multiple fields for
quantities of XRP, IOU, or MPT without duplicating information about the
"issue" (represented by `STIssue`). It is a straightforward serialization of
the `Number` type that uniformly represents those quantities.
---------
Co-authored-by: John Freeman <jfreeman08@gmail.com>
Co-authored-by: Howard Hinnant <howard.hinnant@gmail.com>
* 2.2.2 changed functions acquireAsync and NetworkOPsImp::recvValidation to add an item to a collection under lock, unlock, do some work, then lock again to do remove the item. It will deadlock if an exception is thrown while adding the item - before unlocking.
* Replace ScopedUnlock with scope_unlock.
