Custom stream wrapper support

Added support for custom stream wrappers, such as "fly" or "s3".
Support is determined per reader.

tests/Spout/Reader/CSV/SpoutTestStream.php

@@ -0,0 +1,120 @@
+<?php
+
+namespace Box\Spout\Reader\CSV;
+
+/**
+ * Class SpoutTestStream
+ * Custom stream that reads CSV files located in the tests/resources/csv folder.
+ * For example: spout://foobar will point to tests/resources/csv/foobar.csv
+ *
+ * @package Box\Spout\Reader\CSV
+ */
+class SpoutTestStream
+{
+    const CLASS_NAME = __CLASS__;
+
+    const PATH_TO_CSV_RESOURCES = 'tests/resources/csv/';
+    const CSV_EXTENSION = '.csv';
+
+    /** @var int $position */
+    private $position;
+
+    /** @var resource $fileHandle */
+    private $fileHandle;
+
+    /**
+     * @param string $path
+     * @param int $flag
+     * @return array
+     */
+    public function url_stat($path, $flag)
+    {
+        $filePath = $this->getFilePathFromStreamPath($path);
+        return stat($filePath);
+    }
+
+    /**
+     * @param string $streamPath
+     * @return string
+     */
+    private function getFilePathFromStreamPath($streamPath)
+    {
+        $fileName = parse_url($streamPath, PHP_URL_HOST);
+        return self::PATH_TO_CSV_RESOURCES . $fileName . self::CSV_EXTENSION;
+    }
+
+    /**
+     * @param string $path
+     * @param string $mode
+     * @param int $options
+     * @param string $opened_path
+     * @return bool
+     */
+    public function stream_open($path, $mode, $options, &$opened_path)
+    {
+        $this->position = 0;
+
+        // the path is like "spout://csv_name" so the actual file name correspond the name of the host.
+        $filePath = $this->getFilePathFromStreamPath($path);
+        $this->fileHandle = fopen($filePath, $mode);
+
+        return true;
+    }
+
+    /**
+     * @param int $numBytes
+     * @return string
+     */
+    public function stream_read($numBytes)
+    {
+        $this->position += $numBytes;
+        return fread($this->fileHandle, $numBytes);
+    }
+
+    /**
+     * @return int
+     */
+    public function stream_tell()
+    {
+        return $this->position;
+    }
+
+    /**
+     * @param int $offset
+     * @param int|void $whence
+     * @return bool
+     */
+    public function stream_seek($offset, $whence = SEEK_SET)
+    {
+        $result = fseek($this->fileHandle, $offset, $whence);
+        if ($result === -1) {
+            return false;
+        }
+
+        if ($whence === SEEK_SET) {
+            $this->position = $offset;
+        } else if ($whence === SEEK_CUR) {
+            $this->position += $offset;
+        } else {
+            // not implemented
+        }
+
+        return true;
+    }
+
+    /**
+     * @return bool
+     */
+    public function stream_close()
+    {
+        return fclose($this->fileHandle);
+    }
+
+    /**
+     * @return bool
+     */
+    public function stream_eof()
+    {
+        return feof($this->fileHandle);
+    }
+}