Added config_member type functions

Added basic stuff in the functions: A (for development) required struct
config_member_t variable, a exit_code variable which is set to 1, and
the return statment for the exit_code variable.
removed alloc_initialized for config member type

This function is meant for C applications. I think the lua interpreter
will handle accessing NULLified content inside a config_member_t
automatically (if the newuserdata() function of lua creates a NULLified
memory chunk, what I expect it to do).
added implementation for config member type alloc func
added implementation for copying config members
added implementation for destroying config members
added implementation for destroying config members deep
added implementation for getting a members ident as number