Combine multidimensional NaArray objects
NaArray-abind.RdEXPERIMENTAL!!!
Like ordinary matrices and arrays in base R, NaMatrix objects
can be combined by rows or columns, with rbind() or cbind(),
and multidimensional NaArray objects can be bound along
any dimension with abind().
Note that arbind() can also be used to combine the objects along
their first dimension, and acbind() can be used to combine them
along their second dimension.