* Added `qs` nunjucks filter, which builds query strings from objects
* Added `allowed` option to areas, which limits the item types that will actually be displayed (see `controls` for how to limit what can be added in the editor). You can use a more restrictive `allowed` option to avoid displaying inappropriate widgets in excerpts. Note that rich text must be explicitly included in the list as `richText` or it will not be shown
* Added `aposAreaPlaintext` template helper, which returns a plaintext representation of an area. Note this is true plaintext, so you must escape it with the `e` filter to safely display it as part of HTML. Includes only item types that actually have an appropriate plaintext representation, which currently means richText only, although you can define a getPlaintext method for any item type (such as a widget). Includes a `truncate` option which limits the character count, avoiding word breaks if possible. The truncated text ends with a Unicode ellipsis character
* Added `apos.areaFindFile`, `apos.areaPlaintext` and `apos.truncatePlaintext` for direct access to the above functionality when not going through nunjucks
* Added `self.htmlToPlaintext`, part of the `aposAreaPlaintext` implementation which is likely to be useful separately
* Refactored `apos.partial` so that `apos.getNunjucksEnv` is broken out separately