Renamed 'array destructuring' to 'iterable destructuring'.

In case you didn't know, square-bracket destructuring works on any iterable, not just arrays.

This also re-compiles es6/index.html.
Merge pull request #308 from webbedspace/vital-fixes

Several fixes for recently discovered bugs
Tentative support for compiler-filtered ES6 test HTML output.

Now, in addition to the normal es6/index.html, special versions whose tests have been pre-compiled with a given compiler. Currently 6to5, esnext and es6-transpiler are used. Polyfills are not yet inserted, nor is the output cleaned up compared to the normal table. Additionally, tests that use eval() or Function() will probably not work.
Fixed a slight bug with the compiled code.

To allow 6to5 to compile the test interiors, they are wrapped in an IIFE. But, this IIFE wasn't being II'd correctly.
Compiler test pages.

 * Compiler test pages are output in a compilers/ subdirectory.
 * Compiler test page output now uses a separate skeleton file.
 * Added Traceur.
 * Added polyfill injection.