Potential security issues and various improvements

  Hi guys,

  Please see some change I did after reviewing the code. I didn't find how to run any tests, so I just ensured the modified code is compiling. There is just one issue I spotted but therefore didn't fixed, it's the malloc wrapper used in DEBUG mode. The memory consumption isn't correctly counted as I mentioned in the file.

  I rewrote the email list builder in the SMTP module, as the previous one was subject to a potential buffer overflow problem. It needs some review I guess.

  I messed a little with the VRRP module, as I spotted the same memory management problem as Jay. Then, I didn't take enough care at what I was merging.

  Hope it helps!