libcore: fix overflow/underflow in range_step
Update tutorial: 1-tuples now exist
Update manual for single-element tuples
Update manual for single-element tuple types
Removing some mutable fields in libstd
Removing no longer needed unsafe blocks
Fix typo in u16 debug info
Update help text to match behavior
auto merge of #5782 : zofrex/rust/doc-1-tuples, r=thestinger

As per [the 0.6 release notes](https://github.com/mozilla/rust/wiki/Doc-detailed-release-notes#06-april-2013) single-element tuples are legal. I spotted a couple of places in the documentation that said otherwise, and propose these changes to them.
auto merge of #5786 : JensNockert/rust/u16-debuginfo-typo, r=catamorphism

A small typo in debuginfo.rs related to the u16 type.
auto merge of #5787 : alexcrichton/rust/less-mut-fields, r=catamorphism

This removes some of the easier instances of mutable fields where the explicit self can just become `&mut self` along with removing some unsafe blocks which aren't necessary any more now that purity is gone.

Most of #4568 is done, except for [one case](https://github.com/alexcrichton/rust/blob/less-mut-fields/src/libcore/vec.rs#L1754) where it looks like it has to do with it being a `const` vector. Removing the unsafe block yields:

```
/Users/alex/code/rust2/src/libcore/vec.rs:1755:12: 1755:16 error: illegal borrow unless pure: creating immutable alias to const vec content
/Users/alex/code/rust2/src/libcore/vec.rs:1755         for self.each |e| {
                                                           ^~~~
/Users/alex/code/rust2/src/libcore/vec.rs:1757:8: 1757:9 note: impure due to access to impure function
/Users/alex/code/rust2/src/libcore/vec.rs:1757         }
                                                       ^
error: aborting due to previous error
```

I also didn't delve too much into removing mutable fields with `Cell` or `transmute` and friends.
Fix comment to match style of surrounding text
Support https protocol for git submodules for rust

Currently submodules are using the git protocol. Git protocol is blocked
by certain corporate networks which makes it difficult to sync the submodules.

Replacing the git protocol with https in order to sync the submodules.
auto merge of #5800 : vivekgalatage/rust/master, r=bstrie

Currently submodules are using the git protocol. Git protocol is blocked
by certain corporate networks which makes it difficult to sync the submodules.

Replacing the git protocol with https in order to sync the submodules.
auto merge of #5788 : danluu/rust/rusti_clear, r=bstrie

The old help text reads "clear the screen", but :clear seems intended to do something completely different. I'm not sure what the intent is. If it's really supposed to clear the screen, not only does it not clear the screen, it does something completely different.

```
rusti> fn foo() { println("called foo!") }
()
rusti> foo();
called foo!
()
rusti> :clear
rusti> foo();
<anon>:34:0: 34:3 error: unresolved name: `foo`.
<anon>:34 foo();
```

Per the contributor guidelines, here's the reason there's no testcase: it's a comment string.
auto merge of #5769 : gifnksm/rust/range_step, r=bstrie

`uint::range_step` or `int::range_step` causes overflow or underflow as following.
code:
```rust
fn main() {
    for uint::range_step(3, 0, -2) |n| {
        println(fmt!("%u", n));
    }
}
```
output:
```
3
1
18446744073709551615
18446744073709551613
...
```
This commit fixes this behavior as follows.
```
3
1
```
Bump version to 0.7-rc