Racoon experiment 1

For your consideration.  I have fixed a few issues I was having with using IPSec VPNs.  These patches, at least for me, fix the following issues:

* Dead tunnel if a client connects to an IP address previous used recently.
* Dead tunnel if a client connects to an IP address from a session that has timed out.
* Mac OS X authentication prompts after 48 minutes.

There is a ticket that shows many having a problem with the first two.

https://redmine.pfsense.org/issues/1351

I have tested these patches with the following clients:

* MacOS X Mountain Lion builtin VPN client.
* IOS (5.x 6.x)
* Cisco VPN client v5.0 on Windows 7
* Shrew Soft VPN Client 2.2.1 on Windows 7

Thanks for your time and consideration.