Properly bind nested pattern bindings when there's more than one

Fixes #15488.
Implemented Decodable/Encodable for Cell and RefCell. Fixes #15395

Updated PR with fixme and test

Updated PR with fixme and test
auto merge of #15411 : mitchmindtree/rust/master, r=alexcrichton

I ran `make check` and everything went smoothly. I also tested `#[deriving(Decodable, Encodable)]` on a struct containing both Cell<T> and RefCell<T> and everything now seems to work fine.
manual: Fix typo.

Also removes redundant newline in code block.
auto merge of #15489 : jakub-/rust/issue-15488, r=pcwalton

Fixes #15488.
auto merge of #15496 : ruud-v-a/rust/patch-1, r=huonw

Also removes redundant newline in code block.
style: Clean up most comment delimeters

Clean up the majority of Rust's comments so they match the preferred style.
Discussion @ issue #15458.