Cpp support LmHandlerMsgDisplay.h

[adixmasz]

Can I ask for:

#ifdef __cplusplus
extern "C"
{
#endif`

// Source code in header

#ifdef __cplusplus
}
#endif

In file LmHandlerMsgDisplay.h
I must add it manualy at each library update.

[mluis1]

I have created an issue in order to not forget to apply this recommendation. #1184