Improve detection of sync filters that are not in sync

[Nicklas Nordborg]

There are some situations where the view page of an item list reports that "List appears to be in sync with filters" even if that is not the case:

• If the "child item must exist" is changed to "child item must not exist" (or any other combination)
• If the filter group (see #2232) is changed it may cause a filter to be applied later (or sooner) in the synchronization process. It may also change the filter between INCLUDE and EXCLUDE.
• If items are added or removed manually
• And probably some more things...

It would be nice if we could detect most (all?) changes and display then display the "May not be in sync" warning.

[Nicklas Nordborg]

In 7883:

References #2233: Improve detection of sync filters that are not in sync

Changing properties on a filter that may affect the result should now be detected. A concatenated string if properties that are used in the sync are stored in the lastSyncProperties and can be matched against current properties.

The final size of the list after a synchronization as well as the MD5 of the id for all members is now saved. This information can be compared to current status allowing us to detect if items are manuallt added or removed.