keep getActivity() for compatibility with older code

Author: codeanticode

core/src/processing/core/PApplet.java

@@ -33,6 +33,7 @@
 import java.util.regex.*;
 import java.util.zip.*;
 
+import android.app.Activity;
 import android.content.*;
 import android.content.pm.PackageManager;
 import android.content.res.AssetManager;
@@ -467,6 +468,11 @@ public PSurface getSurface() {
   }
 
 
+  public Activity getActivity() {
+    return surface.getActivity();
+  }
+
+
   public void initSurface(AppComponent component, SurfaceHolder holder) {
     parentLayout = -1;
     initSurface(null, null,  null, component, holder);