The dumb3d->glm / utilities-simplification refactor replaced the old custom
clamp() (which tolerated Lo>Hi, returning the upper bound) with std::clamp,
where inverted bounds are undefined behaviour. Only a few sites were patched
afterwards, by hand, with std::minmax plumbing (incl. a stray `static` inside
a per-axle loop). Others silently produced wrong results in the AI braking /
acceleration path.
Add a safe_clamp() helper (normalizes inverted bounds) and use it ONLY where
Lo<=Hi cannot be proven at compile time (config min/max pairs, sign-dependent
expressions, container underflow). Sites with constant bounds or [0, x>=0]
keep std::clamp. Remove the manual std::minmax workarounds and rewrite the
damaged-track jolt code value-first.
- 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`.
