[reSIProcate] fault during shutdown in InviteSessionCreator.cxx

[justin.matthews at ivr.com]

Hello,	
	Dum will crash when calling shutdown if no offer has been created
for an initial dialog set.  This was tested by sending an INVITE request to
nowhere and then immediately shutting down the stack.  Could someone please
update svn?  
	The crash occurs in the destructor:

InviteSessionCreator::~InviteSessionCreator()
{
	delete mInitialOffer;
}

I fixed this by initializing mInitialOffer to NULL on construction and
adding the following on destruction:
--------------
InviteSessionCreator::InviteSessionCreator(DialogUsageManager& dum, 
                                           const NameAddr& target, 
                                           const NameAddr& from,
                                           const SdpContents* initial, 
                                           ServerSubscriptionHandle
serverSub)
   : BaseCreator(dum),
     mState(Initialized),
     mServerSub(serverSub),
     mInitialOffer(NULL)
{
---------------------
InviteSessionCreator::~InviteSessionCreator()
{	
    if( NULL != mInitialOffer )
    {
        delete mInitialOffer;
        mInitialOffer = NULL;
    }
}
----------------

Thanks,

Justin Matthews