transmitted like a common status code (fix for BB), AdditionalFolders
API and statically shared folders work always with backendids (they are
internally mapped and transmitted with integerIds), 
expose integerIds in the listing of the AdditionalFolders API as
"syncfolderid", generate integerid when an additional folder is added,
have ZPush::$addSyncFolders and
DeviceManager()->GetAdditionalUserSyncFolders() always work on
backendIds, ZPush::GetAdditionalSyncFolders() can return integerIds as
keys if requested (default as backendIds), do Backend->Setup() with
backendIds in ChangesMemoryWrapper, backendfolderid needs to be set in
SyncParameters unsetdata, allow Notes folders as additional static
folders.

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