Reduce diagnostics publishing default to 200 ms (microsoft#1972)

* Remove stale reference

* Don't suppress LHS diagnostics on augmented assign

* Revert "Don't suppress LHS diagnostics on augmented assign"

This reverts commit 6109ac7.

* Escape [ and ]

* PR feedback

* Reduce diagnostics delay

* Change default

Author: Mikhail Arkhipov

src/LanguageServer/Impl/LanguageServer.Configuration.cs

@@ -115,7 +115,7 @@ void AppendToMap(JToken setting, int prefixLength, Dictionary<string, object> ma
         private void HandleDiagnosticsChanges(JToken pythonSection, LanguageServerSettings settings) {
             var analysis = pythonSection["analysis"];
 
-            settings.diagnosticPublishDelay = GetSetting(analysis, "diagnosticPublishDelay", 1000);
+            settings.diagnosticPublishDelay = GetSetting(analysis, "diagnosticPublishDelay", 200);
             var ds = _services.GetService<IDiagnosticsService>();
             ds.PublishingDelay = settings.diagnosticPublishDelay;
 

src/LanguageServer/Impl/LanguageServerSettings.cs

@@ -16,7 +16,7 @@
 
 namespace Microsoft.Python.LanguageServer.Implementation {
     public sealed class LanguageServerSettings: ServerSettings {
-        public int diagnosticPublishDelay = 1000;
+        public int diagnosticPublishDelay = 200;
         public int symbolsHierarchyDepthLimit = 10;
         public int symbolsHierarchyMaxSymbols = 1000;
     }