Add an extra tileSize on the top/left borders
Add an extra tileSize on the top/left borders

As the 'origin' of each tile is the top-left, we need to extend that
clip plane by a tile to guarantee we don't clip a tile whose edge is
still visible.

Should fix tiles being clipped at the top-left corner

pmprog/OpenApoc,AndO3131/OpenApoc,FranciscoDA/OpenApoc,Istrebitel/OpenApoc,steveschnepp/OpenApoc,Istrebitel/OpenApoc,AndO3131/OpenApoc,ShadowDancer/OpenApoc,FranciscoDA/OpenApoc,pmprog/OpenApoc,steveschnepp/OpenApoc,ShadowDancer/OpenApoc,FranciscoDA/OpenApoc,AndO3131/OpenApoc