There are two reasons for renaming the `options` object to `config`:

**First**, it's more consistent. The file that creates this object is
called `config.js`, and the function that creates the object is called
`configFrom()`, and yet the object ends up getting called `options` (but
you have to look in another file, `main.js`, to find this out).

`config` is also used elsewhere as the name for the main configuration
object, for example in Pyramid/h, in the client docs ("Configuring the
Client", "configuration settings") and public API
(`class="js-hypothesis-config"` scripts and `window.hypothesisConfig()`
functions), etc.

These "options" that the `src/annotator/` code reads from the host page
also end up getting renamed to `hostPageConfig` when they get passed
over in to the `src/sidebar/` code.

**Second**, it's more unique. There are a number of other objects in the
`src/annotator/` code that are called options, sometimes the main
options object and another local options object are even used in the
same function. There's no other objects called config.