stop using dplyr::bind_rows in flywire2fafb

* again this *used* to work and not sure if dplyr has become fussier, it's an R 4 thing or
  a change on the spine server
* speed difference is negligible when dealing with matrices or even in rbinds favour
  (no tibble overhead)

R/flywire-coord.R

@@ -156,7 +156,7 @@ flywire2fafb <- function(xyz, method=c("mapmany", "map1"), chunksize=40e3,
       chunkstoread=seq_len(nchunks)
       b=by(xyzraw, chunks, as.matrix)
       l=t(pbapply::pblapply(b, mapmany, ...))
-      mapres=dplyr::bind_rows(l)
+      mapres=do.call(rbind, l)
     }
   }
   # let's get the xy deltas; dz is always 0