Codechange: Remove direct access to _colour_gradient.

Access is now through GetColourGradient, which ensures parameters are in range.

Codechange: Split CT_INVALID into CT_INVALID and INVALID_CARGO.

INVALID_CARGO is a CargoID and should be used for most purposes in game.
CT_INVALID is a CargoType used for defining default properties.

Codechange: Add Rect version of FillDrawPixelInfo().

This simplifies most callers as they longer have to split out a rect.

Codechange: Remove FONT_HEIGHT_... macros. (#11481)

These make it look like we're dealing with a constant, but actually each is a call to `GetCharacterHeight(...)`.

Codechange: cleanup CargoPacket in terms of variable/function names (#11278)

Over the years, things got reused and changed, making the current
names somewhat unclear in what they actually mean and do.

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

Codechange: Base CargoArray off std::array.

This avoids needing to define array accessors and allows use of
default value initialization.

Codechange: Use IsValidCargoID/IsValidCargoType.

IsValidCargoType() is used only for unmapped IDs.

Fix #10032: Capacities of articulated vehicles in build window

See also: #9954

Fix #10114: Wonky depot layout. (#10191)

Depot lists internal layout was not handled well. This is improved by
throwing more Rects at it:
- Vehicle images are now be vertically centred in the rect.
- Image clipping is relaxed to cover the rect, improving larger sprites.
- Outline highlight is now aware of bevel thickness.

Change: Use power-of-2 scaling for some dimensions in GUI.

These are related to drawing sprites that are normally drawn on the
landscape, and should therefore still follow power-of-2 scaling to fit
correctly.

Codechange: Template DoCommandP 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.

(svn r18781) -Codechange: pass the CommandCost to the callback instead of whether it succeeded or not.
-Fix: AIs did update their last cost incorrectly in network games if the cost of the DC_EXEC phase differed from the ~DC_EXEC phase.