Add ability to generate 8 unit wide antlines

[vrad-exe]

Add the ability for the compiler to convert antlines to be 8 units wide, so P1 antlines can look correct. You'd probably want to take all the antline corners and shrink them towards the closest corner of whatever tile they're on, then add the straight segments going between those. That should do it in a consistent way that prevents the corners from misaligning from each other.

Ideally other sizes (4, 2, 1, non-power-of-two?) should be supported too, in case custom styles want to use them.

[TeamSpen210]

The hard part is the corners, since I might need to generate additional straight segments to link up the corners.

[vrad-exe]

That would just be if you have 2 corners right next to each other, right? Still seems doable, maybe tricky if you hardcoded the antline generation entirely around 16 unit antlines though (which, frankly, would have been really stupid given P1 has existed and had this problem for years)

[TeamSpen210]

It's tricky since there's a lot of situations that I need to make sure works - flat, around corners, more unusual cases where there might be branching antlines, etc...