Add sockopt ZMQ_RCVTIMEO/ZMQ_SNDTIMEO.

- Add doc and tests
- Add options and setup
- Wait using poll/select

Signed-off-by: Fabien Ninoles <fabien@tzone.org>
Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

src/mailbox.hpp

@@ -41,7 +41,7 @@ namespace zmq
 
         fd_t get_fd ();
         void send (const command_t &cmd_);
-        int recv (command_t *cmd_, bool block_);
+        int recv (command_t *cmd_, int timeout_);
         
     private:
 
@@ -52,6 +52,11 @@ namespace zmq
         //  Platform-dependent function to create a socketpair.
         static int make_socketpair (fd_t *r_, fd_t *w_);
 
+        //  Receives a command with the specific timeout.
+        //  This function is not to be used for non-blocking or inifinitely
+        //  blocking recvs.
+        int recv_timeout (command_t *cmd_, int timeout_);
+
         //  Disable copying of mailbox_t object.
         mailbox_t (const mailbox_t&);
         const mailbox_t &operator = (const mailbox_t&);