libcore: fix overflow/underflow in range_step
Update help text to match behavior
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-pre
auto merge of #5805 : brson/rust/0.7-pre, r=brson
auto merge of #5766 : thestinger/rust/cmp, r=brson

It was simpler to just give the variants a value instead of listing out all the cases for (*self, *other) in a match statement or writing spaghetti code. This makes the `cmp` method easier to use with FFI too, since you're a cast away from an idiomatic C comparator function. It would be fine implemented another way though.
initial iterator library