Add AreaStore data structure

README.txt

build/android/jni/Android.mk

doc/lua_api.txt

src/CMakeLists.txt

src/areastore.cpp

src/areastore.h

src/cmake_config.h.in

src/script/lua_api/CMakeLists.txt

src/script/lua_api/l_areastore.cpp

src/script/lua_api/l_areastore.h

src/script/lua_api/l_util.cpp

src/script/scripting_game.cpp

src/unittest/CMakeLists.txt

src/unittest/test_areastore.cpp

src/util/container.h