graphics.js will still be built by `./build full`, and once it already exists, `./build` will rebuild it when it's modified. Fixes #1150
It should now be possible to build from a fresh checkout with `node build`.
We no longer have the relevant Githook for automatic building, so putting it in `githooks/` no longer makes much sense. It's now manually called with a build script `./build`, like other PS websites (most notably PSDex and the damagecalc).
