librustc: Remove `~EXPR`, `~TYPE`, and `~PAT` from the language, except
for `~str`/`~[]`.

Note that `~self` still remains, since I forgot to add support for
`Box<self>` before the snapshot.

How to update your code:

* Instead of `~EXPR`, you should write `box EXPR`.

* Instead of `~TYPE`, you should write `Box<Type>`.

* Instead of `~PATTERN`, you should write `box PATTERN`.

[breaking-change]
auto merge of #13958 : pcwalton/rust/detilde, r=pcwalton

for `~str`/`~[]`.

Note that `~self` still remains, since I forgot to add support for
`Box<self>` before the snapshot.

r? @brson or @alexcrichton or whoever
flate: add documentation
arena: add docs for Arena
num: expand crate documentation + add example
term: add docs and windows support

Closes #2807
syntax: update for libterm fallout
time: crate description
workcache: add crate doc block
test: update for term fallout
Add WinConsole docs
Update for master