make the global Highlighter streamable

src/ce_d2syn.pas

@@ -265,6 +265,7 @@ end;
 constructor TSynD2Syn.create(aOwner: TComponent);
 begin
 	inherited create(aOwner);
+  SetSubComponent(true);
 
   DefaultFilter:= 'D source|*.d|D interface|*.di';
 

src/ce_txtsyn.pas

@@ -59,6 +59,7 @@ uses
 constructor TSynTxtSyn.create(aOwner: TComponent);
 begin
   inherited;
+  SetSubComponent(true);
   //
   fSymAttribs := TSynHighlighterAttributes.Create('Symbols', 'Symbols');
   fTxtAttribs := TSynHighlighterAttributes.Create('Text', 'Text');