Also add backend_kw to FieldDataset

src/OutputReaders/field_dataset.jl

@@ -1,7 +1,8 @@
-struct FieldDataset{F, M, P}
+struct FieldDataset{F, M, P, KW}
     fields :: F
     metadata :: M
     filepath :: P
+    backend_kw :: KW
 end
 
 """
@@ -22,17 +23,24 @@ linearly.
   `file["metadata"]`.
 
 - `grid`: May be specified to override the grid used in the JLD2 file.
+
+- `backend_kw`: A dictionary of keyword arguments to pass to the backend (currently only JLD2)
+                to be used when opening files.
 """
 function FieldDataset(filepath;
-                      architecture=CPU(), grid=nothing, backend=InMemory(), metadata_paths=["metadata"])
+                      architecture = CPU(),
+                      grid = nothing,
+                      backend = InMemory(),
+                      metadata_paths = ["metadata"],
+                      backend_kw = Dict{Symbol, Any}())
 
-  file = jldopen(filepath)
+  file = jldopen(filepath; backend_kw...)
 
   field_names = keys(file["timeseries"])
   filter!(k -> k != "t", field_names)  # Time is not a field.
 
   ds = Dict{String, FieldTimeSeries}(
-      name => FieldTimeSeries(filepath, name; architecture, backend, grid)
+      name => FieldTimeSeries(filepath, name; architecture, backend, grid, backend_kw)
       for name in field_names
   )
 
@@ -44,7 +52,7 @@ function FieldDataset(filepath;
 
   close(file)
 
-  return FieldDataset(ds, metadata, abspath(filepath))
+  return FieldDataset(ds, metadata, abspath(filepath), backend_kw)
 end
 
 Base.getindex(fds::FieldDataset, inds...) = Base.getindex(fds.fields, inds...)