Fixed takeLast doc block, demo updates (#76)

Author: davidwdan

demo/average/average.php

@@ -4,17 +4,4 @@
 
 $source = Rx\Observable::range(0, 9)->average();
 
-$subscription = $source->subscribeCallback(
-    function ($x) {
-        echo 'Next: ' . $x . PHP_EOL;
-    },
-    function ($err) {
-        echo 'Error: ' . $err . PHP_EOL;
-    },
-    function () {
-        echo 'Completed' . PHP_EOL;
-    }
-);
-
-// => Next: 4
-// => Completed
+$subscription = $source->subscribe($stdoutObserver);

demo/average/average.php.expect

@@ -1,2 +1,2 @@
-Next: 4
-Completed
+Next value: 4
+Complete!

demo/pluck/pluck.php

@@ -9,19 +9,4 @@
 ])
     ->pluck('value');
 
-$subscription = $source->subscribeCallback(
-    function ($x) {
-        echo 'Next: ' . $x . PHP_EOL;
-    },
-    function ($err) {
-        echo 'Error: ' . $err . PHP_EOL;
-    },
-    function () {
-        echo 'Completed' . PHP_EOL;
-    }
-);
-
-// => Next: 0
-// => Next: 1
-// => Next: 2
-// => Completed
+$subscription = $source->subscribe($stdoutObserver);

demo/pluck/pluck.php.expect

@@ -1,4 +1,5 @@
-Next: 0
-Next: 1
-Next: 2
-Completed
+Next value: 0
+Next value: 1
+Next value: 2
+Complete!
+

demo/sum/sum.php

@@ -5,16 +5,4 @@
 $source = Rx\Observable::range(1, 10)
     ->sum();
 
-$subscription = $source->subscribeCallback(
-    function ($x) {
-        echo 'Next: ' . $x . PHP_EOL;
-    },
-    function ($err) {
-        echo 'Error: ' . $err . PHP_EOL;
-    },
-    function () {
-        echo 'Completed' . PHP_EOL;
-    });
-
-// => Next: 55
-// => Completed
+$subscription = $source->subscribe($stdoutObserver);

demo/sum/sum.php.expect

@@ -1,2 +1,2 @@
-Next: 55
-Completed
+Next value: 55
+Complete!

lib/Rx/Observable.php

@@ -641,7 +641,7 @@ public function takeWhileWithIndex(callable $predicate)
      *
      * @demo take/takeLast.php
      * @operator
-     * @reactivex takelast
+     * @reactivex takeLast
      */
     public function takeLast($count)
     {