noGrammar preference and README

Signed-off-by: Nikolas Komonen <nikolaskomonen@gmail.com>

Author: NikolasKomonen

package.json

@@ -176,6 +176,21 @@
           "default": "hint",
           "description": "The message severity when a document has no associated grammar.",
           "scope": "window"
+        },
+        "xml.diagnostics.enabled": {
+          "type": "boolean",
+          "default": true,
+          "enum": [true, false],
+          "description": "Enable/disable all diagnostics.",
+          "scope": "window"
+        }
+        ,
+        "xml.diagnostics.schema": {
+          "type": "boolean",
+          "default": true,
+          "enum": [true, false],
+          "description": "Enable/disable schema based diagnostics.",
+          "scope": "window"
         }
       }
     },

src/extension.ts

@@ -102,6 +102,7 @@ export function activate(context: ExtensionContext) {
   function getXMLSettings(): JSON {
     let configXML = workspace.getConfiguration().get('xml');
     let xml;
+    configXML = null;
     if (!configXML) { //Set default preferences if not provided
       const defaultValue = 
       {