Add: [Script] GetAirportNumHelipads (#12085)

Adds a function for Scripts to get the number of helipads of an airport type.

Fix #11629: AirportGetNearestTown for rotated airports (#11631)

Add rotation parameter to AirportGetNearestTown
Add wrapper for existing stations
Remove unnecessary iterator cloning

Fix: AirportGetNearestTown incorrectly assumed first TileIterator result was origin. (#11565)

Not all TileIterators are equal, and some do not start at the top-corner, so the perimeter check was wrong. As the caller already has thie origin tile, use that instead.

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

Add: precondition checks to functions that work with both valid company and deity

These are functions that either use ScriptObject::Command or ScriptObject::GetCompany.
This is a bit over-protective, but having the check everywhere makes it easier to
validate that no check is missing automatically instead of by review.

At this moment these checks will not do anything useful, as either IsValid or
IsDeity from ScriptCompanyMode returns true, but that will change later.

Codechange: use GSCompanyMode::IsValid, IsDeity, and the precondition helpers

Direct 1:1 replacements in the code, and comments now refer to either
GSCompanyMode::IsValid or GSCompanyMode::IsDeity instead of several variations
on "company mode active" or "no company mode active".

Codechange: Distance between town and airport has already just been found, so use it. (#7427)

Previously the distance was thrown away, only to be expensively recalculated again.

Add: AI/GS GetMonthlyMaintenanceCost (#6897)

API addition which allows AI/GS scripts to retrieve the monthly maintenance cost of an airport type.