Use better api for svgd init

Author: ferrine

docs/source/notebooks/variational_api_quickstart.ipynb

@@ -1310,8 +1310,9 @@
    "source": [
     "with model:\n",
     "    # We'll use SVGD\n",
-    "    # So creating empirical approximation in advance is a good decision\n",
-    "    approx = pm.Empirical.from_noise(size=500, jitter=1)\n",
+    "    inference = pm.SVGD(n_particles=500, jitter=1)\n",
+    "    # shortcut reference to approximation\n",
+    "    approx = inference.approx\n",
     "    # Here we need `more_replacements` to change train_set to test_set\n",
     "    test_probs = approx.sample_node(z, more_replacements={\n",
     "        Xt: X_test\n",
@@ -1342,17 +1343,6 @@
     "train_accuracy = train_ok.mean(-1)"
    ]
   },
-  {
-   "cell_type": "code",
-   "execution_count": 56,
-   "metadata": {
-    "collapsed": true
-   },
-   "outputs": [],
-   "source": [
-    "inference = pm.SVGD(histogram=approx)"
-   ]
-  },
   {
    "cell_type": "markdown",
    "metadata": {},