[uriutils] rewrite CreateArchivePath() to return a CURL
[filesystem] adds IDirectory::AllowAll() to take over from IDirectory::IsAllowed to save CURL processing
[filesystem] convert IDirectory interface to use CURL
[filesystem] utilise CURL versions of HasExtension/GetFileName in IsAllowed
[filesystem] adds CURL versions of CDirectory::GetDirectory, CFile::Cache and CFile::Exist
[filesystem] switch directory factory Create() calls to CURL
[cosmetic] minor cleanup in CDirectoryFactory::Create
[zip/rar] tidy up zip/rar directory code to use new CURL functions
[filesystem] use CURL based URIUtils::SubstitutePath in CDirectory/CFile/CFileStream
[smartplaylist] use CURL for reading XML from files
[filesystem] cleanup CFileDirectoryFactory to use the CURL we pass into it where possible