* Core part of built-in translation library

* Test coverage for translation library

* Plural forms evaluator

* Add plural forms translation test cases

* Remove dependency on gettext and libintl

* Remove libintl-lite for Android

* Rename ngettext to n_gettext to avoid collision with libintl.h

* Improve InvalidTranslationDocumentException diagnostic message

* Fix raw_string_format not supporting positional arguments on Windows

Sourced from https://github.com/gulrak/filesystem/releases/tag/v1.5.8

This is a C++17 compliant `std::filesystem` polyfill. When included via
`ghc/fs_std.hpp`, it will delegate to the actual implementation when
available, populating the methods in the namespace `fs`. When not available,
its own implementations will be in the same namespace.

* Updated BINDIST_EXTRAS

* Rename LICENSE-OFL-Terminus-Font.TXT to LICENSE-OFL-Terminus-Font.txt

* Update LICENSE.txt

* Use libbacktrace to generate backtrace

* Move dbghelp symbol initialization to debug_write_backtrace

* Use libbacktrace on cross-compilation to Windows

* Download prebuilt libbacktrace before building

* Use square brackets instead of angle brackets

* Add license text of libbacktrace

Conflicts:
	CataclysmWin.cbp
	Makefile.Windows
	SIGNOFF
	TRANSLATING.md
	addiction.cpp
	artifact.cpp
	auto_pickup.cpp
	bionics.cpp
	calendar.cpp
	computer.cpp
	construction.cpp
	crafting.cpp
	data/raw/item_groups.json
	data/raw/items/ammo.json
	data/raw/items/armor.json
	data/raw/items/comestibles.json
	data/raw/items/containers.json
	data/raw/items/melee.json
	data/raw/items/ranged.json
	data/raw/professions.json
	data/raw/recipes.json
	disease.cpp
	faction.cpp
	field.cpp
	game.cpp
	game.h
	item.cpp
	item.h
	item_factory.cpp
	itypedef.cpp
	iuse.cpp
	lang/po/cataclysm-dda.pot
	lang/po/de_DE.po
	lang/po/fr_FR.po
	lang/po/pt_PT.po
	lang/po/ru_RU.po
	lang/po/zh_CN.po
	main.cpp
	melee.cpp
	monattack.cpp
	mondeath.cpp
	monmove.cpp
	mutation.cpp
	mutation_data.cpp
	newcharacter.cpp
	npcmove.cpp
	npctalk.cpp
	options.cpp
	options.h
	output.cpp
	output.h
	overmap.cpp
	player.cpp
	player.h
	pldata.h
	profession.cpp
	profession.h
	ranged.cpp
	sdlcurse.cpp
	skill.cpp
	translations.h
	trapfunc.cpp
	veh_interact.cpp
	vehicle.cpp
	weather.cpp
	wincurse.cpp
	wish.cpp