Change: Decouple and remove landscape-dependent cargo types. (#11719)

Cargo types of default engines, industries and houses are now specified in terms of label.

Feature: NewGRF properties to set town production effect and multiplier. (#11947)

Town production effect is modelled on town acceptance (growth) effect, and so takes an original cargo slot for behaviour instead of a direct value.

NewGRF feature 0x0B, property 0x1E, takes 1 byte.

Valid values are:
- 0x00 to behave like passengers
- 0x02 to behave like mail
- 0xFF to behave like other cargo (i.e. not produced.)

If not set, town production effect is set based on the cargo label ('PASS' or 'MAIL').

Town production multiplier allows adjusting the amount of cargo produces when Town Production Effect is set, without needing to use callbacks.

NewGRF feature 0x0B (cargo), property 0x1F, accepts a 2 byte (word) value, similar to the cargo capacity multiplier property. The default value is 256 which means 100%, i.e. normal rate.

Change: Towns generate cargo based on town production effect.

This replaces the fixed handling of passengers and mail.

Codechange: Rename TownEffect to TownAcceptanceEffect.

This makes it clearer that TownEffect only affects acceptance behaviour.

Codechange: Be consistent with how we name common parameters

TileIndex is always tile and Town is always *t. Don't use t and *town.

Codechange: Rename TryClearTile() for clarity

The function does not execute the clearing action.

Codechange: Use consistent name for bay road stops

As of #10494, this is how we describe original dead-end road stops.

Codechange: Add base() method to StrongType to allow access to the base type without casting. (#11445)

This removes the ability to explicitly cast to the base type, but the requirement
to use .base() means the conversion is still explicit.

Codechange: make explicit when a TileIndex is cast to its basetype (#11190)

This prevents people accidentially assigning a TileIndex to a Date
or any other type they shouldn't.

Codechange: automatic adding of _t to (u)int types, and WChar to char32_t

for i in `find src -type f|grep -v 3rdparty/fmt|grep -v 3rdparty/catch2|grep -v 3rdparty/opengl|grep -v stdafx.h`; do sed 's/uint16& /uint16 \&/g;s/int8\([ >*),;[]\)/int8_t\1/g;s/int16\([ >*),;[]\)/int16_t\1/g;s/int32\([ >*),;[]\)/int32_t\1/g;s/int64\([ >*),;[]\)/int64_t\1/g;s/ uint32(/ uint32_t(/g;s/_uint8_t/_uint8/;s/Uint8_t/Uint8/;s/ft_int64_t/ft_int64/g;s/uint64$/uint64_t/;s/WChar/char32_t/g;s/char32_t char32_t/char32_t WChar/' -i $i; done

Change: make Exclusive Transport Rights more exclusive (#11076)

Now, exclusive transport rights can only be bought if no company
currently owns them. A successful bribe will void any exclusive
transport rights that any *other* company currently has in the town.

Codechange: Use IsValidCargoID/IsValidCargoType.

IsValidCargoType() is used only for unmapped IDs.

Codechange: Make SpriteType, CargoSortType, SourceType and ScriptType enum classes. (#10663)

This avoids a (soft) namespace conflict between the four ST_* enums.

Fix #10343: Don't extend town-disallowed roadtypes. (#10347)

Towns currently don't build disallowed roadtypes, however they should
also not extend disallowed roadtypes as well.

If the roadtype that cannot be extended happens to be the roadtype that
the town was going to build then this restriction is ignored.

Codechange: pass "ground vehicle" to GetTileSlopeZ since for tunnel/bridges there are two states

Previously it checked the position in non-driving direction to "guess" whether
a ground vehicle was using the function, so on tunnels/bridges it could either
return the Z of the (virtual) ground compared to the Z of the path the vehicle
would take.

Fix #10150: Force FS_SMALL for small viewport signs. (#10283)

* Fix #10150: Force FS_SMALL for small viewport signs.

This is a workaround for string widths being different with mixed
font-sizes.

* Fix: Flag small sign shadow as small text.

(This method of drawing shadows is hilarious and needs replacing, but
this is a quick fix.)

Codechange: Template DoCommand to automagically reflect the parameters of the command proc.

When finished, this will allow each command handler to take individually
different parameters, obliviating the need for bit-packing.

Codechange: Let the compile generate the master command table out of templated command traits.

This is using a non-intrusive type-traits like templated system, which
allows compile-time validation that the command table and the command
enum match up.

Fix #9407: desync when founding a town nearby a station (#9526)

"stations_near" wasn't updated when founding a town near
a station. As this variable is not saved, any client joining
after the town is founded has a different value for
"stations_near", potentially causing desyncs.

As the intention of this if() statement was to skip an expensive
calculation when there are clearly no stations, better to move
that check inside the function, so other places also enjoy
the speedup.

Codechange: use "[[maybe_unused]]" instead of a wide variety of other ways we had

While at it, replace OTTD_ASSERT with WITH_ASSERT, as this
is always set if assert() is valid. No matter if NDEBUG is set
or not.

Codechange: Apply coding style (#8640)

* Fix: Missing or needed spaces

* Codechange: Remove space

* Codechange: Remove space

* Codechange: More missing spaces

* Codechange: Missing spaces

* Codechange: Remove space

* Codechange: Remove space

Revert 78f92130: "Fix #8506: Towns shouldn't add junctions to NewGRF roads they cannot build (#8535)" (#8541)

As per https://github.com/OpenTTD/OpenTTD/pull/8535#issuecomment-757122918,
jumped the gun here.

Fix #7604: prevent houses to wander too far from town center when rebuilding (#8507)

When a multi-tile house is rebuild, it always used the most northern
tile to build the new house. This can very easily lead to houses
wandering off in the north-ish direction (either NW or NE).

To prevent this, pick the tile closest to town center when rebuilding
on a multi-tile house. This still means a house can be build away
from a road, but it is no longer wandering around finding another
town to call home.

Change: towns can now bridge 4 rails (up from 3)

Having 4 rails is a pretty common design, and towns now couldn't
bridge out of this common design.