On a million-instance scenery (tomaszewo) the infra pass was spending ~24s
reopening pure-visual leaf twins (grass.incb etc.) just to skip their content --
~200k cParser constructions, because every flora include reopens the same leaf.
Twin header now flags whether a file has any infrastructure node or include
(format bumped to v10). A pure-visual leaf (flora .incb: triangles + transform
directives only) has it clear, so the infra pass skips opening it: the first open
of each file caches the verdict, later opens are dropped before construction.
Result on tomaszewo: infra 55s -> 31s, getToken 1.06M -> 89k. Also adds a load
profiler (per-type build time, dispatch time, getToken count) behind WriteLog so
the next bottleneck is measured, not guessed (it's now the 25s of decorative
vehicle media loading).
- The `TMoverParameters::derail()` function has been renamed to `::Derail()`, with a capital D.
- All derail events now use that function.
- Simplified and unified the logic behind different derail types.
- The `dtrack_freerail` track type is now slightly increasing the chance of derailing on a tight curve, as it was the intention.
- A new `DerailReason` enum has been created which holds all derail types.
- The `DerailReason` field in the `TMoverParameters` class has been removed.
- This was a transient field which is not necessary anymore.
- The logging functionality as such has been moved from `DynObj.cpp` to `Mover.cpp`.
