Fix pointer types in the manual.
DST raw pointers - *-pointers are fat pointers
auto merge of #16924 : steveklabnik/rust/manual_pointer_fix, r=pcwalton

This was brought up in IRC: https://botbot.me/mozilla/rust/2014-08-30/?msg=20733803&page=26
Reviewer changes
auto merge of #16805 : nick29581/rust/dst-raw, r=nikomatsakis

r? @pnkfelix or @nikomatsakis
Add unnecessary_import_braces lint.

The lint checks any unnecessary braces around one imported item like
`use std::num::{abs};`.

Signed-off-by: OGINO Masanori <masanori.ogino@gmail.com>
Make unnecessary_import_braces warn-by-default.

Signed-off-by: OGINO Masanori <masanori.ogino@gmail.com>