Fixed crash with entities in unloaded chunks
Fixed crash with entities in unloaded chunks

* Fixes #1190

mmdk95/cuberite,Tri125/MCServer,birkett/MCServer,birkett/cuberite,linnemannr/MCServer,tonibm19/cuberite,tonibm19/cuberite,SamOatesPlugins/cuberite,linnemannr/MCServer,Howaner/MCServer,mjssw/cuberite,kevinr/cuberite,thetaeo/cuberite,mmdk95/cuberite,nicodinh/cuberite,QUSpilPrgm/cuberite,birkett/MCServer,kevinr/cuberite,birkett/cuberite,mc-server/MCServer,nichwall/cuberite,marvinkopf/cuberite,birkett/MCServer,tonibm19/cuberite,guijun/MCServer,jammet/MCServer,mmdk95/cuberite,zackp30/cuberite,nichwall/cuberite,guijun/MCServer,nounoursheureux/MCServer,SamOatesPlugins/cuberite,Haxi52/cuberite,Tri125/MCServer,electromatter/cuberite,ionux/MCServer,thetaeo/cuberite,nounoursheureux/MCServer,mjssw/cuberite,HelenaKitty/EbooMC,zackp30/cuberite,mjssw/cuberite,bendl/cuberite,mmdk95/cuberite,Haxi52/cuberite,electromatter/cuberite,Frownigami1/cuberite,QUSpilPrgm/cuberite,jammet/MCServer,mjssw/cuberite,tonibm19/cuberite,QUSpilPrgm/cuberite,Tri125/MCServer,zackp30/cuberite,zackp30/cuberite,mjssw/cuberite,Haxi52/cuberite,linnemannr/MCServer,marvinkopf/cuberite,Schwertspize/cuberite,Howaner/MCServer,nichwall/cuberite,Tri125/MCServer,electromatter/cuberite,guijun/MCServer,johnsoch/cuberite,nounoursheureux/MCServer,ionux/MCServer,kevinr/cuberite,nevercast/cuberite,birkett/MCServer,Frownigami1/cuberite,nicodinh/cuberite,Howaner/MCServer,linnemannr/MCServer,Schwertspize/cuberite,johnsoch/cuberite,zackp30/cuberite,QUSpilPrgm/cuberite,marvinkopf/cuberite,SamOatesPlugins/cuberite,johnsoch/cuberite,electromatter/cuberite,guijun/MCServer,tonibm19/cuberite,jammet/MCServer,nichwall/cuberite,HelenaKitty/EbooMC,Fighter19/cuberite,jammet/MCServer,Altenius/cuberite,Howaner/MCServer,mc-server/MCServer,Howaner/MCServer,nicodinh/cuberite,thetaeo/cuberite,Altenius/cuberite,Haxi52/cuberite,Schwertspize/cuberite,SamOatesPlugins/cuberite,electromatter/cuberite,nicodinh/cuberite,SamOatesPlugins/cuberite,Altenius/cuberite,HelenaKitty/EbooMC,birkett/cuberite,birkett/cuberite,guijun/MCServer,thetaeo/cuberite,mc-server/MCServer,Schwertspize/cuberite,Altenius/cuberite,Schwertspize/cuberite,Tri125/MCServer,nounoursheureux/MCServer,nounoursheureux/MCServer,bendl/cuberite,thetaeo/cuberite,linnemannr/MCServer,nevercast/cuberite,Howaner/MCServer,Fighter19/cuberite,ionux/MCServer,tonibm19/cuberite,nevercast/cuberite,bendl/cuberite,mmdk95/cuberite,Haxi52/cuberite,HelenaKitty/EbooMC,nichwall/cuberite,nounoursheureux/MCServer,birkett/cuberite,Tri125/MCServer,marvinkopf/cuberite,mc-server/MCServer,nicodinh/cuberite,nevercast/cuberite,mc-server/MCServer,mjssw/cuberite,jammet/MCServer,ionux/MCServer,nevercast/cuberite,nicodinh/cuberite,marvinkopf/cuberite,Fighter19/cuberite,mmdk95/cuberite,zackp30/cuberite,johnsoch/cuberite,Fighter19/cuberite,nichwall/cuberite,thetaeo/cuberite,Haxi52/cuberite,Fighter19/cuberite,QUSpilPrgm/cuberite,kevinr/cuberite,Frownigami1/cuberite,birkett/MCServer,electromatter/cuberite,mc-server/MCServer,bendl/cuberite,Frownigami1/cuberite,marvinkopf/cuberite,kevinr/cuberite,birkett/MCServer,Frownigami1/cuberite,johnsoch/cuberite,ionux/MCServer,nevercast/cuberite,QUSpilPrgm/cuberite,HelenaKitty/EbooMC,bendl/cuberite,guijun/MCServer,Fighter19/cuberite,kevinr/cuberite,jammet/MCServer,Altenius/cuberite,ionux/MCServer,birkett/cuberite,linnemannr/MCServer