define __all__ to make wildcard import work (#719)

diff --git a/src/OpenSSL/SSL.py b/src/OpenSSL/SSL.py
index 39b7bdc..32c038a 100644
--- a/src/OpenSSL/SSL.py
+++ b/src/OpenSSL/SSL.py
@@ -27,6 +27,95 @@
 from OpenSSL.crypto import (
     FILETYPE_PEM, _PassphraseHelper, PKey, X509Name, X509, X509Store)
 
+__all__ = [
+    'OPENSSL_VERSION_NUMBER',
+    'SSLEAY_VERSION',
+    'SSLEAY_CFLAGS',
+    'SSLEAY_PLATFORM',
+    'SSLEAY_DIR',
+    'SSLEAY_BUILT_ON',
+    'SENT_SHUTDOWN',
+    'RECEIVED_SHUTDOWN',
+    'SSLv2_METHOD',
+    'SSLv3_METHOD',
+    'SSLv23_METHOD',
+    'TLSv1_METHOD',
+    'TLSv1_1_METHOD',
+    'TLSv1_2_METHOD',
+    'OP_NO_SSLv2',
+    'OP_NO_SSLv3',
+    'OP_NO_TLSv1',
+    'OP_NO_TLSv1_1',
+    'OP_NO_TLSv1_2',
+    'MODE_RELEASE_BUFFERS',
+    'OP_SINGLE_DH_USE',
+    'OP_SINGLE_ECDH_USE',
+    'OP_EPHEMERAL_RSA',
+    'OP_MICROSOFT_SESS_ID_BUG',
+    'OP_NETSCAPE_CHALLENGE_BUG',
+    'OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG',
+    'OP_SSLREF2_REUSE_CERT_TYPE_BUG',
+    'OP_MICROSOFT_BIG_SSLV3_BUFFER',
+    'OP_MSIE_SSLV2_RSA_PADDING',
+    'OP_SSLEAY_080_CLIENT_DH_BUG',
+    'OP_TLS_D5_BUG',
+    'OP_TLS_BLOCK_PADDING_BUG',
+    'OP_DONT_INSERT_EMPTY_FRAGMENTS',
+    'OP_CIPHER_SERVER_PREFERENCE',
+    'OP_TLS_ROLLBACK_BUG',
+    'OP_PKCS1_CHECK_1',
+    'OP_PKCS1_CHECK_2',
+    'OP_NETSCAPE_CA_DN_BUG',
+    'OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG',
+    'OP_NO_COMPRESSION',
+    'OP_NO_QUERY_MTU',
+    'OP_COOKIE_EXCHANGE',
+    'OP_NO_TICKET',
+    'OP_ALL',
+    'VERIFY_PEER',
+    'VERIFY_FAIL_IF_NO_PEER_CERT',
+    'VERIFY_CLIENT_ONCE',
+    'VERIFY_NONE',
+    'SESS_CACHE_OFF',
+    'SESS_CACHE_CLIENT',
+    'SESS_CACHE_SERVER',
+    'SESS_CACHE_BOTH',
+    'SESS_CACHE_NO_AUTO_CLEAR',
+    'SESS_CACHE_NO_INTERNAL_LOOKUP',
+    'SESS_CACHE_NO_INTERNAL_STORE',
+    'SESS_CACHE_NO_INTERNAL',
+    'SSL_ST_CONNECT',
+    'SSL_ST_ACCEPT',
+    'SSL_ST_MASK',
+    'SSL_ST_INIT',
+    'SSL_ST_BEFORE',
+    'SSL_ST_OK',
+    'SSL_ST_RENEGOTIATE',
+    'SSL_CB_LOOP',
+    'SSL_CB_EXIT',
+    'SSL_CB_READ',
+    'SSL_CB_WRITE',
+    'SSL_CB_ALERT',
+    'SSL_CB_READ_ALERT',
+    'SSL_CB_WRITE_ALERT',
+    'SSL_CB_ACCEPT_LOOP',
+    'SSL_CB_ACCEPT_EXIT',
+    'SSL_CB_CONNECT_LOOP',
+    'SSL_CB_CONNECT_EXIT',
+    'SSL_CB_HANDSHAKE_START',
+    'SSL_CB_HANDSHAKE_DONE',
+    'Error',
+    'WantReadError',
+    'WantWriteError',
+    'WantX509LookupError',
+    'ZeroReturnError',
+    'SysCallError',
+    'SSLeay_version',
+    'Session',
+    'Context',
+    'Connection'
+]
+
 try:
     _memoryview = memoryview
 except NameError: