Fix trail overlap

[Kestrellius]

This makes a change to the way trails are rendered in order to remedy an issue where trail segments would visibly "overlap" with themselves when twisted. It does this by increasing the number of tris in each segment from 2 to 4. This appears to have a significant performance impact in very trail-heavy scenarios, so the change only takes effect when particle detail is set to max. (I would be entirely willing to switch it to a different detail setting, like model, if that's deemed more appropriate.)

More profiling would be useful in future to figure out exactly where the performance drop is coming from, but for now, under typical circumstances, it should be fine.