Add Gdn_Request->AssetRoot() to decouple the root of static assets from the root of dispatched requests.
Add Gdn_Request->UrlDomain().

This is a convenience function for conditionally getting the current domain in various formats.
Change Asset() and SmartAsset() to use Gdn_Request->AssetRoot().
Fix bug in the Emoji class where Url() was called instead of Asset().
Merge branch 'hotfix/locale-name-fix' into feature/decouple-request-root
Add the asset_url smarty modifier.
Remove unused variable.
Fix the smarty_modifier_asset_url() function.
Merge pull request #2166 from vanilla/feature/decouple-request-root

Decouple the static asset root from the web root.