Fix: [NewGRF] Ensure that stations always have an even number of sprite layouts.
The drawing code has a special fallbacks for zero layouts, but fails hard for one layout.
(odd numbers >= 3 are weird, but do not fail as badly as 1)

Add: [NewGRF] Map seed as global variable.

This is useful to provide a feature-agnostic, stable random value that differs between games.
One of the possible uses is to e.g. use it to create pseudo-random regions for towns or industries.

Codechange: Remove CargoSpec::multipliertowngrowth which is unused (#9701)

This is set by cargo property 19.
This property is only implemented in TTDPatch.

Fix a4987233: NewGRFs could no longer be loaded from the NewGRF folder.

This statement was removed by accident, as it felt it could be removed.
But it is used to know if the NewGRF is from the baseset folder or
from the NewGRF folder.

Change: Skip creating a RealSpriteGroup when there is only one result.

This avoids checking RSG for empty sets every time they are evaluated.
This might alter behaviour in cases of a malformed NewGRF file.

Codechange: rename str_validate to StrMakeValid(InPlace) (#9304)

This to be more explicit the function changes the value, and not
returns yes/no.

Codechange: comparison result is always the same due to earlier check

Practically the length of the handlers not being equal to the number of
features is the problem as it means something was forgotten when adding
a new feature, so static assert to that and let the existing check on
the feature number take care of invalid data from the NewGRFs.

Feature: Define refittability of default vehicles using cargo classes.

This ensures that default vehicles can transport any NewGRF defined cargos, albeit with weird graphics and vehicle names.
This also changes the refittability of default vehicles with default industries.

Fix: Resolve cargo-types of default vehicles via their cargo label.

Default vehicles now behave as if they had a cargo translation table. This fixes default vehicles carrying seemingly random cargos, if NewGRF industry sets are present.
This behavior is disabled, when a NewGRF touches any of the cargo-type or refitting properties. In that case it's up to the NewGRF to define its own cargo translation table.

Codechange: Use std::vector for NewGRF station platform layouts.

This avoids the need to custom memory management and additional members.

This also resolves use-after-free if modifying copied layouts, so presumably nobody has ever done that.

Codechange: Warn if randomaction2 group count is not a power of 2.

Previously noted by a comment, this does not need to be guarded against as non-powers of 2 will not cause issues beyond the choice of results being reduced.

Change: rename setting "max_heightlevel" to "map_height_limit"

This better reflects what it is, and hopefully removes a bit of
the confusion people are having what this setting actually does.

Additionally, update the text on the setting to better inform
users what it is doing exactly, so they can make an educated
decision on how to change it.

Next commit will introduce an "auto" value, which should be the
new default. The rename has as added benefit that everyone will
start out on the "auto" value.

Fix: [NewGRF] Action 7/9 conditions 0x0F to 0x12 failed, if 'param' was 0x88. (#8382)

Fix: [NewGRF] Action 7/9 conditions 0x0B to 0x12 failed, if 'param' was 0x85.
These conditions are supposed to ignore 'param' entirely.

Fix #8166: don't crash on loading an invalid roadtype newgrf

Initialization code for GRFFile::roadtype_map was copied from
railtype_map. But while RailType is a byte-sized enum and could thus
be initialized via memset, RoadType doesn't have a defined size.

Codechange: Replace SmallPair with std::pair.

std::pair is already the smallest possible pair, and it already handles non-POD types correctly.

Feature: NewGRF callback profiling (#7868)

Adds a console command newgrf_profile to collect some profiling data about NewGRF action 2 callbacks and produce a CSV file.

Fix e66cec8f86: Permit loading of industry production callback with invalid cargo type.

It is only an error if the invalid result is actually used. This will be silently ignored at the moment.
It is still an error if a duplicate cargo type is returned.

Add: Houses can accept up to 16 different cargo types via NewGRF.

New Action0 property 23 for feature 07, variable length, format B n*(B B). Initial byte is number of structures following. First byte in structure is cargo id, second is acceptance level in 1/8 units.

Codechange #6729: mute bogus GCC 7 warning (#6733)

We do a memset of (byte - byte), which strictly seen ranges from -254 .. 255, for which GCC warns.
But just before this memset is an if() which says the first byte has to be bigger than the second.
So this is a bogus warning.

(svn r27989) -Fix (r27985): VA2 optimisation failed in various special cases:
- nvar=0 is meant to return the calculated result.
- Missing references resolve to NULL and got identified with the default result.
- Missing 'break' broke overlapping cases.
- Splitting into non-overlapping cases could result in more than 256 cases.

(svn r27730) -Change: Split openttd.grf into openttd.grf and orig_extra.grf
openttd.grf is now always loaded and provides all extra graphics in case the (possibly outdated) baseset does not.
orig_extra.grf contains graphics specific to the original baseset only.