Use plain arrays instead of Edges and Vertices containers

Refs graphp/graph#195

Author: clue

composer.json

@@ -10,7 +10,7 @@
     },
     "require": {
         "php": ">=5.3.0",
-        "graphp/graph": "dev-master#a9d8cfc as 1.0.0"
+        "graphp/graph": "dev-master#214de45 as 1.0.0"
     },
     "require-dev": {
         "phpunit/phpunit": "^9.3 || ^5.7 || ^4.8.35"

src/GraphViz.php

@@ -305,7 +305,7 @@ public function createScript(Graph $graph)
                 $vid = $vids[\spl_object_hash($vertex)];
                 $layout = $this->getLayoutVertex($vertex, $vid);
 
-                if ($layout || $vertex->getEdges()->isEmpty()) {
+                if ($layout || !$vertex->getEdges()) {
                     $script .= $this->formatIndent . $this->escape($vid);
                     if ($layout) {
                         $script .= ' ' . $this->escapeAttributes($layout);
@@ -319,7 +319,7 @@ public function createScript(Graph $graph)
 
         // add all edges as directed edges
         foreach ($graph->getEdges() as $currentEdge) {
-            $both = $currentEdge->getVertices()->getVector();
+            $both = $currentEdge->getVertices();
             $currentStartVertex = $both[0];
             $currentTargetVertex = $both[1];