Server crash while zoning

[Jabantiz]

I noticed this while zoning in and out of cave of illboding in frost fang sea while working on instances. When I zoned back into frost fang every now and then the server would crash, always in player::ShouldSendSpawn() It seems to have been an invalid spawn passed to that function even though we check to see if it is valid multiple times before it is sent. I think this comes from the mutexmap that is maintained in the zoneserver.

To prevent the crash I added a try catch around the code in ShouldSendSpawn(), this should prevent the world from crapping out when this happens. This is just a way to mask the problem though, we need to figure out what is going wrong and where to fix this properly and hopefully figure out some of the other invalid pointer issues.