Fix reading left side bearings

Before this change php-font-lib would only populate as many glyph metrics as were present in the hmtx table. However, per the spec, "if numberOfHMetrics is less than the total number of glyphs, then the hMetrics array is followed by an array for the left side bearing values of the remaining glyphs."

Author: ren1244

src/FontLib/Table/Type/hmtx.php

@@ -35,8 +35,14 @@ protected function _parse() {
     }
 
     if ($numOfLongHorMetrics < $numGlyphs) {
-      $lastWidth = end($data);
-      $data      = array_pad($data, $numGlyphs, $lastWidth);
+      $lastWidth = end($data)[0];
+      $numLeft   = $numGlyphs - $numOfLongHorMetrics;
+      $metrics   = $font->readUInt16Many($numLeft);
+      for($i = 0; $i < $numLeft; $i++) {
+        $gid             = $numOfLongHorMetrics + $i;
+        $leftSideBearing = isset($metrics[$i]) ? $metrics[$i] : 0;
+        $data[$gid]      = array($lastWidth, $leftSideBearing);
+      }
     }
 
     $this->data = $data;