Organized modules, added indirection for FFI vs extension loading (#10)

* mv src -> ext, lib -> src to be more in line with PHP module expectations

* Fixed dependency for ffi test

* Fixed path in format-check to C source

* CRT will now try the extension first, then FFI

src/AWS/CRT/CRT.php

@@ -0,0 +1,72 @@
+<?php
+
+namespace AWS\CRT;
+
+use AWS\CRT\Internal\Extension;
+use AWS\CRT\Internal\FFI;
+
+use \RuntimeException;
+
+/**
+ * Wrapper for the interface to the CRT. There only ever needs to be one of these, but
+ * additional instances won't cost anything other than their memory.
+ * Creating an instance of any NativeResource will activate the CRT binding. User code
+ * should only need to create one of these if they are only accessing CRT:: static functions.
+ */
+final class CRT {
+
+    private static $impl = null;
+    private static $refcount = 0;
+
+    function __construct() {
+        if (is_null(self::$impl)) {
+            try {
+                self::$impl = new Extension();
+            } catch (RuntimeException $rex) {
+                try {
+                    self::$impl = new FFI();
+                } catch (RuntimeException $frex) {
+                    throw new RuntimeException('Unable to initialize AWS CRT via extension or FFI', -1, $frex);
+                }
+            }
+        }
+        ++self::$refcount;
+    }
+
+    function __destruct() {
+        if (--self::$refcount == 0) {
+            self::$impl = null;
+        }
+    }
+
+    /**
+     * @return integer last error code reported within the CRT
+     */
+    public static function last_error() {
+        return self::$impl->aws_crt_last_error();
+    }
+
+    /**
+     * @param integer $error Error code from the CRT, usually delivered via callback or {@see last_error}
+     * @return string Human-readable description of the provided error code
+     */
+    public static function error_str($error) {
+        return self::$impl->aws_crt_error_str((int) $error);
+    }
+
+    /**
+     * @param integer $error Error code from the CRT, usually delivered via callback or {@see last_error}
+     * @return string Name/enum identifier for the provided error code
+     */
+    public static function error_name($error) {
+        return self::$impl->aws_crt_error_name((int) $error);
+    }
+
+    function event_loop_group_new($num_threads) {
+        return self::$impl->aws_crt_event_loop_group_new($num_threads);
+    }
+
+    function event_loop_group_release($elg) {
+        return self::$impl->aws_crt_event_loop_group_release($elg);
+    }
+}