Avoid copy of BasisWithOperators objects
Things like the one found at https://code.ornl.gov/gonzalo_3/dmrgpp/blob/features/src/Engine/Truncation.h#L249 can perhaps be avoided.
Things like the one found at https://code.ornl.gov/gonzalo_3/dmrgpp/blob/features/src/Engine/Truncation.h#L249 can perhaps be avoided.