Pretty-printer doesn't preserve blank lines

[brson]

I think it used to but it must have broke. The following turns into a wall of code:

         let cfilename = cinfo.ident;
         let cdata = cinfo.data;

         // Claim this crate number and cache it
         let cnum = e.next_crate_num;
         e.crate_cache.insert(ident, cnum);
         e.next_crate_num += 1;

         // Now resolve the crates referenced by this crate
         let cnum_map = resolve_crate_deps(e, cdata);

         let cmeta = {name: ident, data: cdata, cnum_map: cnum_map};

[brson]

Fixt