Make LANGUAGE switchable in runtime (#653)

squashed into a single commit because doing it in steps that all
compiled involved a lot of boilerplate that is pointless to commit to
the repository. GH still has the PR for reference.

g_lang, MAX_MESSAGES_ON_MAP_BOTTOM, and GetLanguagePrefix() were
compile-time constants selected by the ENGLISH/GERMAN/... build
define. They're now runtime, defaulting to the same per-exe value the
define used to pick, and overridable at startup from [Ja2 Settings]
LANGUAGE in Ja2.ini.

-

XMLTacticalMessages is filled at runtime from NewTacticalMessages.xml,
never from compiled-in per-language data: all 8 per-language definitions
were the identical all-zero { L"" }. Delete them and define one shared
buffer in Utils/XML_Language.cpp (the loader) instead of pointer-rebinding
it like the static tables — this drops 9 dead 800KB zero-buffers (8
namespaced copies in LanguageStrings.cpp plus the standalone one) and
leaves no bind-ordering hazard for the XML load path.

-

ExportStrings.cpp privately recompiled one language's full text table
by #including the raw _<LANG>Text.cpp inside namespace Loc, keyed off
the exe-level ENGLISH/GERMAN/... compile macro (whichever the build
happened to select). That's redundant with the pointer globals every
other subsystem already uses (Text.h / LanguageStrings.cpp).

Drop the private copy; the unqualified table names in Loc::ExportStrings
now resolve to the global pointer externs, which BindLanguageStrings has
already rebound to the runtime g_lang by the time this runs (EXPORT_STRINGS
ini flag, checked after GetRuntimeSettings in sgp.cpp). gs_Lang (used only
by Loc::Translate for the Polish/Russian byte remap on raw .edt exports) is
now derived from g_lang via ToLocLanguage, so the export always matches
whatever language is actually active instead of a compile-time pick.

-

Editor/popupmenu.cpp and Strategic/Scheduling.cpp kept their own
call-site extern of gszScheduleActions as CHAR16[NUM_SCHEDULE_ACTIONS][20]
after the real definition changed into a rebindable pointer
(CHAR16 (*)[20], LanguageStrings.cpp). MSVC decays the outer array
dimension when mangling globals, so both declarations produce the same
symbol (?gszScheduleActions@@3PAY0BE@_WA) and the mismatch linked
silently -- but the array-typed TUs then indexed the 4-byte pointer
slot itself as string data, so the editor schedule popup and the map
schedule message text read garbage.

-

add text.def to be single-source of truth on symbol names and use it
 .much simpler, less error prone if adding more strings

-

add pseudo interface for language state. MAX_SAGES_ON_BOTTOM must always
 change in lockstep with g_lang. this isn't foolproof but better

---------

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

cmake/CopyUserPresetTemplate.cmake

@@ -1,6 +1,5 @@
 function(CopyUserPresetTemplate)
 	if(
-		NOT DEFINED Languages AND
 		NOT DEFINED Applications AND
 		NOT EXISTS "${CMAKE_SOURCE_DIR}/CMakePresets.json" AND
 		NOT EXISTS "${CMAKE_SOURCE_DIR}/CMakeUserPresets.json"

cmake/presets/CMakePresets.json

@@ -7,8 +7,6 @@
       "generator": "Ninja",
       "binaryDir": "${sourceDir}/build/${presetName}",
       "cacheVariables": {
-        // Valid choices: ENGLISH;GERMAN;FRENCH;ITALIAN;POLISH;DUTCH;RUSSIAN;CHINESE. If empty (""), will configure all.
-        "Languages": "ENGLISH",
         // Valid choices: JA2;JA2MAPEDITOR;JA2UB;JA2UBMAPEDITOR. If empty (""), will configure all.
         "Applications": "JA2",
         // For debugging: enter your desired gamedir. e.g. C:/Games/JA2