[reSIProcate] More problems with `assert'

[Daniel Pocock]

I occasionally see this piece of code causing trouble, assert at 
approximately line 1166 of DialogUsageManager.cxx (see code below).

Is it satisfactory to change the `assert' to something less 
catastrophic, like this for example:

#include <typeinfo>
...
if(dynamic_cast<SipMessage*>(msg.get()) == 0)
{
   ErrorLog(<< "discarding message of type " << 
typeid(*(msg.get())).name() <<", transaction gone away perhaps?");
   msg.release();
   return;
}

// From DialogUsageManager.cxx:

   if (tid != Data::Empty && !mIncomingFeatureList.empty())
   {
      FeatureChainMap::iterator it;
      //efficiently find or create FeatureChain, should prob. be a 
utility template
      {
         FeatureChainMap::iterator lb = 
mIncomingFeatureChainMap.lower_bound(tid);
         if (lb != mIncomingFeatureChainMap.end() && 
!(mIncomingFeatureChainMap.key_comp()(tid, lb->first)))
         {
            it = lb;
         }
         else
         {
            assert(dynamic_cast<SipMessage*>(msg.get()));
            it = mIncomingFeatureChainMap.insert(lb, 
FeatureChainMap::value_type(tid, new DumFeatureChain(*this, 
mIncomingFeatureList, *mIncomingTarget)));
         }
      }

      DumFeatureChain::ProcessingResult res = 
it->second->process(msg.get());