Added a new function: AddNewEvent, which only adds an event to the list if it doesn't already exist. Kept the old one as it might me useful to be able to add an event more than once.
#this file is included only when system Lua library is not found
file(GLOB lua_src *.c *.h)
set(LIBRARY_OUTPUT_PATH ${EXECUTABLE_OUTPUT_PATH})
if(WIN32)
add_definitions(-DLUA_BUILD_AS_DLL)
add_library(lua SHARED ${lua_src})
set_target_properties(lua PROPERTIES PREFIX "")
install(TARGETS lua RUNTIME DESTINATION ${target_dir})
else(WIN32)
add_definitions(-DLUA_USE_LINUX)
add_library(lua STATIC ${lua_src})
endif(WIN32)