Mark OLESEN authored Jul 25, 2023 and Mark OLESEN committed Aug 30, 2023

- nonBlocking: receive before send

- nonBlocking: wait for receive requests, process and then wait for
  other requests. Can be extended to use polling...

- the 'fake' send (to self) now send copies into recv buffers instead
  of send buffers.
  This provides a clear separation of send and receive fields

- avoid unnecessary reallocations with PtrList of send/recv buffers

- remove outer looping for accessAndFlip and pass target field
  as parameter for inner looping instead

ENH: refine mapDistribute send/recv requests handling

- separate send/recv requests for finer control
- receive does not need access to PtrList of sendBuffers, since the
  send-to-self now uses the recvBuffers