parallel selector matching
Remove unused rust-http-client
Upgrade the Rust compiler
Upgrade submodules
Add default formatters for Au and Range
fmt! -> format!
Add a helper for ignoring the EOF condition so we don't crash
Other language changes
Remove unnecessary format!s
Store the Page's final URL before parsing

We were parsing URLs like

    //bits.wikimedia.org/static-1.22wmf22/skins/vector/images/search-ltr.png?303-4

as local filenames because HTMLImageElement::update_image didn't have a
current_url to pass to make_url().
Update reftest runner for new Rust
Touch rust-auto-clean-trigger
Fix logging to account for lack of Default.
Update submodules.
auto merge of #1163 : metajack/servo/kmc-rust-upgrade, r=kmcallister

Most work courtesy of @kmcallister.

I already reviewed Keegan's work, so just the last two commits need attention.
Log CSS errors on stderr, with serialized bits of CSS.
auto merge of #1156 : SimonSapin/servo/logging, r=kmcallister

(Ab)using `error!()` because it’s enabled by default.
auto merge of #1152 : ILyoan/servo/parallel_selector_matching, r=SimonSapin

This an attempt to parallelize selector matching.

Approach
* Let the `match_subtree` spawn limited number of tasks.
* Each of them takes a list of nodes that is uniformly distributed
* And then each task does the selector matching for every single node in its list.

(Not sure if this is worthwhile for long term especially considering CSS optimizing techniques such as ancestor filter or style sharing)

Benchmark from my machine (LayoutSelectorMatchCategory) (intel i7 3.4GHz * 8, linux x86_64)
* src/test/demo.html
 * original: 0.07ms
 * parallel: 0.20ms
* perf-rainbow.html
 * original: 485ms
 * parallel: 245ms
* A test page with 15000 nodes and 3000 CSS selector(including inline style).
 * original: 140ms
 * parallel: 60ms
Update rust-cssparser for visibility rules.
Only export an explicit public API in the style crate

I.e. make every module private by default.