Now using SFTP stream wrapper from phpseclib

- Upgraded phpseclib to master version (post 0.3.5)
- Now using fopen() on sftp URL for both read and write
- Fixes #4063

apps/files_external/3rdparty/phpseclib/AUTHORS

@@ -1,3 +1,5 @@
 phpseclib Lead Developer:  TerraFrost (Jim Wigginton)
 
-phpseclib Developers:      monnerat (Patrick Monnerat)
+phpseclib Developers:      monnerat (Patrick Monnerat)
+                           bantu (Andreas Fischer)
+                           petrich (Hans-Jürgen Petrich)

apps/files_external/3rdparty/phpseclib/README.md

@@ -4,9 +4,9 @@
 
 MIT-licensed pure-PHP implementations of an arbitrary-precision integer
 arithmetic library, fully PKCS#1 (v2.1) compliant RSA, DES, 3DES, RC4, Rijndael,
-AES, SSH-1, SSH-2, SFTP, and X.509
+AES, Blowfish, Twofish, SSH-1, SSH-2, SFTP, and X.509
 
-* [Download (0.3.1)](http://sourceforge.net/projects/phpseclib/files/phpseclib0.3.1.zip/download)
+* [Download (0.3.5)](http://sourceforge.net/projects/phpseclib/files/phpseclib0.3.5.zip/download)
 * [Browse Git](https://github.com/phpseclib/phpseclib)
 * [Documentation](http://phpseclib.sourceforge.net/)
 * [Support](http://www.frostjedi.com/phpbb/viewforum.php?f=46)

apps/files_external/3rdparty/phpseclib/composer.json

@@ -43,6 +43,14 @@
             "File": "phpseclib/",
             "Math": "phpseclib/",
             "Net": "phpseclib/"
+        },
+        "files": [
+            "phpseclib/Crypt/Random.php"
+        ]
+    },
+    "extra": {
+        "branch-alias": {
+            "dev-master": "0.3-dev"
         }
     }
 }