Fix TravisCI errors (#33 - #35)

Author: Progi1984

src/PhpPowerpoint/Writer/ODPresentation.php

@@ -163,7 +163,7 @@ public function save($pFilename)
 
             // Add charts
             foreach ($this->chartArray as $keyChart => $shapeChart) {
-                $arrayFile = $this->getWriterPart('charts')->writePart(shapeChart);
+                $arrayFile = $this->getWriterPart('charts')->writePart($shapeChart);
                 foreach ($arrayFile as $file => $content) {
                     if (!empty($content)) {
                         $objZip->addFromString('Object '.$keyChart.'/' . $file, $content);

src/PhpPowerpoint/Writer/ODPresentation/ObjectsChart.php

@@ -519,7 +519,7 @@ private function writeSeries(Chart $chart, Chart\Series $series)
         } elseif ($chartType instanceof Pie3D) {
             $count = $series->getDataPointFills();
             $inc = 0;
-            for ($inc = 0 ; $inc < $count ; $inc++) {
+            for ($inc = 0; $inc < $count; $inc++) {
                 // chart:data-point
                 $this->xmlContent->startElement('chart:data-point');
                 $this->xmlContent->writeAttribute('chart:style-name', 'styleSeries'.$this->numSeries.'_'.$inc);