OPTION(AQUARIA_INTERNAL_LUA "Always use included Lua library" TRUE)
if(AQUARIA_INTERNAL_LUA)
    message(STATUS "Using internal copy of Lua 5.1")
    set(LUA_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/lua-5.1.4/src" CACHE INTERNAL "")
    add_subdirectory(lua-5.1.4)
else()
    find_package(Lua51 REQUIRED)
endif()