44 - nat changes and ike rekey

Text proposal:

Section 4.4

     The initiator receives a NAT_DETECTION_DESTINATION_IP
     notification that does not match the previous UPDATE_SA_ADDRESSES
     response (see Section 4.7 for a more detailed description).

=>

     The initiator receives a NAT_DETECTION_DESTINATION_IP
     notification with a value that does not match the value in a
     previous UPDATE_SA_ADDRESSES response (see Section 4.7
     for a more detailed description).

     Note that this may cause an extra address update when
     IKE rekeying is in progress, because the NAT_DETECTION_DESTINATION_IP
     notification only contains a hash of the address and some
     other values such as the SPIs which change upon IKE rekey.
     Such an extra address update is harmless, however.

--Jari