Fixed supertest fold-down conflicting with column highlighting.

Also, clicking an entire supertest name cell toggles its fold-down, not just the arrow.

Additionally, said arrow now rotates to denote the fold-down status.

Fixes #297, and one of #75.
Fixed the spec link for arrow functions.

It incorrectly pointed to wiki.ecmascript.org instead of the draft spec.
Merge pull request #298 from webbedspace/bugfixes

Fixed supertest fold-down conflicting with column highlighting