Fixed the slab vertical mirroring.
Fixed the slab vertical mirroring.

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