Represents a callback function.
make interface.language.c.c_callback(ctx, retType, paramTypes, mthd, userData): Class constructor.ctx: Library object callback will be used in.retType: Callback's return type.paramTypes: Callback's parameters.mthd: Method to use.userData: Additional user data.destruct interface.language.c.c_callback(): Class destructor._cbk: Internal use only._ctx: Internal use only._func: Internal use only.pointer(): Return pointer for use in function.