add an internationalization constant

gather all ENGLISH|GERMAN|CHINESE etc preprocessor hell into a single
library, so to restrict the number of targets that need to be built 8x

this still has UB/EDITOR definitions so that still needs to be dealt
with before we can build it only 8 times

CMakeLists.txt

@@ -54,6 +54,7 @@ include_directories(
 	"${CMAKE_SOURCE_DIR}/Multiplayer"
 	"${CMAKE_SOURCE_DIR}/Editor"
 	"${CMAKE_SOURCE_DIR}/Console"
+	"${CMAKE_SOURCE_DIR}/i18n/include"
 )
 
 # external libraries
@@ -85,6 +86,7 @@ Editor
 Console
 Tactical
 ModularizedTacticalAI
+i18n
 )
 foreach(lib IN LISTS Ja2_Libs)
 	add_subdirectory(${lib})