Added special allocator for shadow volumes data.
Added special allocator for shadow volumes data.

jpcy/bgfx,emoon/bgfx,Synxis/bgfx,v3n/bgfx,darkimage/bgfx,aonorin/bgfx,mcanthony/bgfx,marco-we/bgfx,janstk/bgfx,ocornut/bgfx,emoon/bgfx,darkimage/bgfx,jdryg/bgfx,fluffyfreak/bgfx,darkimage/bgfx,MikePopoloski/bgfx,sergeScherbakov/bgfx,LWJGL-CI/bgfx,0-wiz-0/bgfx,ocornut/bgfx,marco-we/bgfx,andr3wmac/bgfx,bkaradzic/bgfx,v3n/bgfx,mendsley/bgfx,ming4883/bgfx,ktotheoz/bgfx,jpcy/bgfx,sergeScherbakov/bgfx,Vertexwahn/bgfx,Extrawurst/bgfx,0-wiz-0/bgfx,kondrak/bgfx,cyndis/bgfx,andr3wmac/bgfx,MikePopoloski/bgfx,emoon/bgfx,MikePopoloski/bgfx,janstk/bgfx,mmicko/bgfx,cuavas/bgfx,ktotheoz/bgfx,ocornut/bgfx,sergeScherbakov/bgfx,fluffyfreak/bgfx,LSBOSS/bgfx,v3n/bgfx,BlueCrystalLabs/bgfx,Synxis/bgfx,BlueCrystalLabs/bgfx,Extrawurst/bgfx,septag/bgfx,mendsley/bgfx,kondrak/bgfx,ktotheoz/bgfx,cuavas/bgfx,jdryg/bgfx,jdryg/bgfx,mcanthony/bgfx,jpcy/bgfx,aonorin/bgfx,mendsley/bgfx,Synxis/bgfx,fluffyfreak/bgfx,mmicko/bgfx,LWJGL-CI/bgfx,janstk/bgfx,bkaradzic/bgfx,LSBOSS/bgfx,Vertexwahn/bgfx,marco-we/bgfx,elmindreda/bgfx,attilaz/bgfx,LWJGL-CI/bgfx,septag/bgfx,LSBOSS/bgfx,cyndis/bgfx,cyndis/bgfx,0-wiz-0/bgfx,LWJGL-CI/bgfx,BlueCrystalLabs/bgfx,elmindreda/bgfx,mmicko/bgfx,andr3wmac/bgfx,aonorin/bgfx,ming4883/bgfx,jpcy/bgfx,elmindreda/bgfx,jdryg/bgfx,cuavas/bgfx,Vertexwahn/bgfx,kondrak/bgfx,mcanthony/bgfx,fluffyfreak/bgfx,septag/bgfx,bkaradzic/bgfx,bkaradzic/bgfx,Extrawurst/bgfx,attilaz/bgfx,attilaz/bgfx,ming4883/bgfx