Replace is_object/is_array with switch on gettype

When checking multiple types, this is ~10% slower in the worst case, and ~30-33% faster for the average and best case.

See #218

src/Mustache/Context.php

@@ -172,8 +172,9 @@ class Mustache_Context
     private function findVariableInStack($id, array $stack)
     {
         for ($i = count($stack) - 1; $i >= 0; $i--) {
-            if (is_object($stack[$i]) && !($stack[$i] instanceof Closure)) {
+            switch (gettype($stack[$i])) {
-
+                case 'object':
+                    if (!($stack[$i] instanceof Closure)) {
                         // Note that is_callable() *will not work here*
                         // See https://github.com/bobthecow/mustache.php/wiki/Magic-Methods
                         if (method_exists($stack[$i], $id)) {
@@ -183,9 +184,15 @@ class Mustache_Context
                         } elseif ($stack[$i] instanceof ArrayAccess && isset($stack[$i][$id])) {
                             return $stack[$i][$id];
                         }
-            } elseif (is_array($stack[$i]) && array_key_exists($id, $stack[$i])) {
+                    }
+                    break;
+
+                case 'array':
+                    if (array_key_exists($id, $stack[$i])) {
                         return $stack[$i][$id];
                     }
+                    break;
+            }
         }
 
         return '';

src/Mustache/Template.php

@@ -113,9 +113,11 @@ abstract class Mustache_Template
      */
     protected function isIterable($value)
     {
-        if (is_object($value)) {
+        switch (gettype($value)) {
+            case 'object':
                 return $value instanceof Traversable;
-        } elseif (is_array($value)) {
+
+            case 'array':
                 $i = 0;
                 foreach ($value as $k => $v) {
                     if ($k !== $i++) {
@@ -124,7 +126,8 @@ abstract class Mustache_Template
                 }
 
                 return true;
-        } else {
+
+            default:
                 return false;
         }
     }