Variadic template arguments unpacking

[Max Strakhov]

Artur, if i use your solution like

printf("...", ForEach!(val => conv(val).c_str())(values).tuple);

Than i would get a crash, because all the tuple elements would be 
char*'s, pointing to already freed memory, as std::string's 
destructor gets called each time right after alias function 
exits. Ths is what c++ unpacking operator for: i actually return 
a packed list of std::string's, apply .c_str() to each and than 
unpack the list to current context.