Implement basic support for Pattern element

lib/attributes.js

@@ -161,6 +161,20 @@ const GradientAttributes = {
     }
 };
 
+const PatternAttributes = {
+    ...ViewBoxAttributes,
+    name: true,
+    x: true,
+    y: true,
+    patternwidth: true,
+    patternheight: true,
+    patternUnits: true,
+    patternContentUnits: true,
+    patternTransform: {
+        diff: arrayDiffer
+    }
+};
+
 const LinearGradientAttributes = {
     ...GradientAttributes,
     x1: true,
@@ -240,5 +254,6 @@ export {
     SymbolAttributes,
     LinearGradientAttributes,
     RadialGradientAttributes,
-    ViewBoxAttributes
+    ViewBoxAttributes,
+    PatternAttributes
 };