Ship en_US, sv_SE, misc, geo/SE and geo/US as Go packages exporting FS, listed by data.Modules(), and fail a bare New naming WithDataFS

node.go

@@ -24,6 +24,8 @@ type node interface{ isNode() }
 type folder struct {
 	children map[string]node
 	unloaded map[string]*indexed
+	// reads is, for each category, the modules its source's manifest names it reading by default.
+	reads map[string][]string
 }
 
 func (*folder) isNode() {}
@@ -33,6 +35,17 @@ func (g *folder) put(name string, n node) {
 	delete(g.unloaded, name)
 }
 
+func (g *folder) setReads(name string, reads []string) {
+	if len(reads) == 0 {
+		delete(g.reads, name)
+		return
+	}
+	if g.reads == nil {
+		g.reads = map[string][]string{}
+	}
+	g.reads[name] = reads
+}
+
 func (g *folder) putUnloaded(name string, x *indexed) {
 	delete(g.children, name)
 	if g.unloaded == nil {