- Extensions now have their own pages
- The API for extensions to register permissions and settings has been overhauled via the `flarum/admin/utils/ExtensionData` util
- An extension grid has been added as a widget to the Dashboard page
- Give them a fixed width (independent of font library)
- Center the icons in their column
- De-emphasize the icons by applying a muted color
Fixes#2016, closes#2018.
- Introduce the concept of "required permissions" - basically a permission dependency tree. In order for a group to be granted one permission, they must also have another.
- Improve redraw performance by not building dropdown menu contents until dropdown is opened
ref #904
