The last commit to that repo was 2014, which was before Rust hit 1.0.
The language went through a number of pretty significant changes before 1.0 including renaming a bunch of stuff.
I believe the ~ operator is basically the same as Box::new() but guarentees that the expression will place it's result directly in the box as opposed to placing it on the stack and then moving it into the box. The only reference I could quickly find to it was this RFC though which mostly talks around what it does.
I think int/uint are just isize/usize before being renamed.