Inject the route when creating the adapter, a little less JObject use
New adapter loading API which can support custom objects, proxy old API for B/C
Implement a standardized install path for all extension adapters
Code style fixes
Improving directory exists string (thanks @brianteeman), correct key for createExtensionRoot
Update F/E language file
Fix for installing multiple languages, additional error check for JInstallerHelper::unpack
Fixing installing multiple languages in install app
Do not always create the extension root for packages
Merge pull request #5514 from mbabker/MoreInstallAdapter

Continued JInstallerAdapter implementation - Standard Install Routine