* fix incorrect logic for validating content paths
* remove `includeRules` helper
* generate keyframes as part of the animate plugin
* add matchUtilities
* splitup `variantPlugins` and `corePlugins`
* immediately take the `safelist` values into account
Currently we had to manually add them in the `setupTrackingContext`,
`setupWatchingContext` and the `cli`.
This was a bit cumbersome, because the `safelist` function (to resolve
regex patterns) was implemented on the context. This means that we had
to do something like this:
```js
let changedContent = []
let context = createContext(config, changedContent)
for (let content of context.safelist()) {
changedContent.push(content)
}
```
This just feels wrong in general, so now it is handled internally for
you which means that we can't mess it up anymore in those 3 spots.
* drop the dot from the extension
Our transformers and extractors are implemented for `html` for example.
However the `path.extname()` returns `.html`.
This isn't an issue by default, but it could be for with custom
extractors / transformers.
* normalize the configuration
* make shared cache local per extractor
* ensure we always have an `extension`
Defaults to `html`
* splitup custom-extractors test
* update old config structure to new structure
* ensure we validate the "old" structure, and warn if invalid
* add tests with "old" config, to ensure it keeps working
* add missing `content` object
* inline unnecessary function abstraction
