Add types for hierarchical document symbols

Just exists on a branch of vscode-languageserver-node atm, see microsoft/vscode-languageserver-node#373.

src/languageServerProtocol/Types.hx

@@ -740,6 +740,52 @@ typedef SymbolInformation = {
     var ?containerName:String;
 }
 
+/**
+    Represents programming constructs like variables, classes, interfaces etc.
+    that appear in a document. Document symbols can be hierarchical and they
+    have two ranges: one that encloses its definition and one that points to
+    its most interesting range, e.g. the range of an identifier.
+**/
+typedef DocumentSymbol = {
+    /**
+        The name of this symbol.
+    **/
+    var name:String;
+
+    /**
+        More detail for this symbol, e.g the signature of a function.
+    **/
+    var detail:String;
+
+    /**
+        The kind of this symbol.
+    **/
+    var kind:SymbolKind;
+
+    /**
+        Indicates if this symbol is deprecated.
+    **/
+    var ?deprecated:Bool;
+
+    /**
+        The range enclosing this symbol not including leading/trailing whitespace but everything else
+        like comments. This information is typically used to determine if the the clients cursor is
+        inside the symbol to reveal in the symbol in the UI.
+    **/
+    var range:Range;
+
+    /**
+        The range that should be selected and reveal when this symbol is being picked, e.g the name of a function.
+        Must be contained by the the `range`.
+    **/
+    var selectionRange:Range;
+
+    /**
+        Children of this symbol, e.g. properties of a class.
+    **/
+    var ?children:Array<DocumentSymbol>;
+}
+
 /**
     Parameters for a `DocumentSymbols` request.
 **/

src/languageServerProtocol/protocol/Protocol.hx

@@ -175,7 +175,7 @@ class Methods {
     /**
         The document symbol request is sent from the client to the server to list all symbols found in a given text document.
     **/
-    static inline var DocumentSymbols = new RequestMethod<DocumentSymbolParams,Null<Array<SymbolInformation>>,NoData,TextDocumentRegistrationOptions>("textDocument/documentSymbol");
+    static inline var DocumentSymbols = new RequestMethod<DocumentSymbolParams,Null<Array<EitherType<SymbolInformation,DocumentSymbol>>>,NoData,TextDocumentRegistrationOptions>("textDocument/documentSymbol");
 
     /**
         The workspace symbol request is sent from the client to the server to list project-wide symbols matching the query string.
@@ -599,6 +599,11 @@ typedef TextDocumentClientCapabilities =
             **/
             var ?valueSet:Array<SymbolKind>;
         };
+
+        /**
+            The client support hierarchical document symbols.
+        **/
+        var ?hierarchicalDocumentSymbolSupport:Bool;
     };
 
     /**