PHP namespaces for nested messages and enums (#4536)

* uses namespaces for nested messages and enums

* fixes namespaces for PHP dist

* fixes namespace for Descriptors, adds Cardinality and Kind

* fixes nested namespaces for reserved words and adds tests

* adds tests and generator fix for php class prefixes

* fixes escaping of protobuf packages, enum comments, misc others

* nice refactor of generated code

* adds class files for backwards compatibility

* simplifies code with templates

* adds compatibility files to makefile

* cleanup of generator and fixes nested namespace bug

* regenerates proto types

* remove internal BC classes

* adds deprecated warning, adds methods back

* simplifies if statement

* fixes dist files

* addresses review comments

* adds back TYPE_URL_PREFIX constant

* adds @deprecated to old nested class files

* skips tests which require a separate process when protobuf.so is enabled

* Adds tests for legacy nested classes that do not require separate processes to test

* uses legacy names for GPBUtil message check

* adds block for IDE @deprecated message

* Namespace for nested message/enum in c extension

* Remove unused code

1 files changed, 20 insertions, 3 deletions

diff --git a/php/src/Google/Protobuf/Timestamp.php b/php/src/Google/Protobuf/Timestamp.php
index f2286ab4..e21f3231 100644
--- a/php/src/Google/Protobuf/Timestamp.php
+++ b/php/src/Google/Protobuf/Timestamp.php
@@ -89,9 +89,26 @@ class Timestamp extends \Google\Protobuf\Internal\Message
      */
     private $nanos = 0;
 
-    public function __construct() {
+    /**
+     * Constructor.
+     *
+     * @param array $data {
+     *     Optional. Data for populating the Message object.
+     *
+     *     @type int|string $seconds
+     *           Represents seconds of UTC time since Unix epoch
+     *           1970-01-01T00:00:00Z. Must be from 0001-01-01T00:00:00Z to
+     *           9999-12-31T23:59:59Z inclusive.
+     *     @type int $nanos
+     *           Non-negative fractions of a second at nanosecond resolution. Negative
+     *           second values with fractions must still have non-negative nanos values
+     *           that count forward in time. Must be from 0 to 999,999,999
+     *           inclusive.
+     * }
+     */
+    public function __construct($data = NULL) {
         \GPBMetadata\Google\Protobuf\Timestamp::initOnce();
-        parent::__construct();
+        parent::__construct($data);
     }
 
     /**
@@ -156,7 +173,7 @@ class Timestamp extends \Google\Protobuf\Internal\Message
         return $this;
     }
 
-    /**
+    /*
      * Converts PHP DateTime to Timestamp.
      *
      * @param \DateTime $datetime