Floor fix

I've fixed the width of the train tracks to match the size of the train car. This required me to adjust the service tunnel meshes as well as the floor mesh. Had to do it this way otherwise if I would have changed the train size or the train wheel size in width it would loose its proportions and look bad. The train tracks were a bit too wide anyway so now after the fix they are proper size. I've also added some stone slabs in few places to fill the gaps.