TrackingPolicy::Debug didn't store the base pointer of the Area, and
instead relied on the first allocation to discover it, however, because
of alignment, the first allocation may not match the base pointer.
Because of that there could be an overflow in onRewind(), i.e. we
could rewind to a pointer before the (wrongly computed) base. This
overflow caused the debug memset to go awry and stomped on memory.
This is fixed by passing the base pointer to the constructor of the
TrackingPolicy. This base pointer could be nullptr with certain
allocators, but in that case, onReset/onRewind should never be called;
and this is enforced at compile time.
Also fixed a (luckily) harmless buffer overflow when preparing the
dynamic lights, if the number of lights wasn't a multiple of 4. This
was harmless because we use a linear allocator, so overflows are not
really overflows.
* Minor clean-ups
- fix a couple usage of std::function
- fix a couple usage of std::string
- remove ALIGN_LOOP, which didn't work
- fix a couple explicit/noexcept
- virtual -> override
* Fix spelling typos and other minor clang-tidy
