Rust moving away from GC into reference counting

[Adam D. Ruppe]

I think we could do the whole owned pointer concept in D too, by 
making a struct with a disabled copy constructor. I don't know 
much about Rust's specifics though so not sure if that's an exact 
match.

But I'm already running with the idea that all slices are 
"borrowed", so we could say the same thing about pointers, if you 
have one, assume it is borrowed and you shouldn't store it nor 
free it.