re-introduce chop since it may be a key to the puzzle for hullnums
allow caller to do full fragmentation, add option to force it
fix BrushGE causing liquids, etc to be cut up
removed tree_t parameter from functions that don't need it
pass reference to tree_t instead of ptr
use an enum instead of std::optional<bool> for the ternary value to store split type, since it's more explicit and obvious now what the three values do
use some explicit types (bspbrush_t::ptr for pointer, bspbrush_t::container for container of pointers, and bspbrush_t::make_ptr to create one) so that we can swap it out with different pointers easier later
swap out bspbrush_t::ptr from unique_ptr to shared_ptr; it's not important yet, but it does not increase compilation time and will allow us to pass things to functions like SplitBrush without destroying the original as long as we still have a reference to it somewhere (important for ChopBrushes)
add get_positive_plane to mapface_t
instead of creating a whole copy of the bspbrush_t list, BrushBSP now just creates copies of the shared_ptrs which are then filtered down the tree; the originals are never modified by SplitBrushList and friends, only split into new brushes, so this is safe from what I can tell
portals now directly reference the mapface_ts
original_brushes now directly reference the mapbrush_ts
early exit in `BrushBSP` if brush list is empty (moved to top)
"node_t::original_brushes" is now only used during construction and cleared on Prune; original_mapbrushes is used to track the map brushes on nodes post-construction
calculate and cache contents on mapbrush_t
pass through the "use mid split" boolean again
remove node_t::side; appeared to be unused in our current code, and needs to be removed anyways to support the other plane splitters
re-introduce ChooseMidPlaneFromList, but comment it out as it currently fails on a lot of BSPs.
Eric Wasylishen
Jonathan