Trigger slow-sync when hashtable get malformed/deleted

[dgollub]

Deleting of hashtable.db can cause unexpected synchronization results: e.g. duplicates.

Plugins which rely on the hashtable need to get the chance to detect if the hashtable got deleted and a slow-sync is required.

Otherwise a missing/deleted hashtable would end-up in a plugin which reports _every_ entry as new change in a fast-sync -> duplicates.

This scenario got reported by ticket 901 comment 8.

[henrik]

This should be up to the individual plugins.

If there is no hashtable (either first sync or it has been removed) the plugin should simply request a slowsync.

Same goes for anchor.db

Not so sure about archive.db; I don't know what it is doing, but looks like some engine stuff that the plugins are not aware of.

[dgollub]

Still present for trunk i guess ...

[dgollub]

(In [5986]) Marshal/Denmarshal? the slow-sync attribute of a ObjtypeSink?. This is required to trigger a slow-sync in the initailze state. This coudl happen in case the hashtable got deleted.

see #960

[dgollub]

(In [5987]) Add a parameter in osync_hashtable_new to allow to report that the hashtable got newly created. This helps to identify that the hashtable might got deleted. This is useful to report a slowsync in this case

see #960

[dgollub]

(In [5988]) Set slow-sync for ObjTypeSink? if the hashtable got deleted.

refs #960

[dgollub]

(In [5989]) Fix build of test/support.o this got broken with previous commit when introducing a new parameter to osync_hashtable_new

refs #960

[dgollub]

(In [5990]) remove debugging statement/printf

refs #960

[dgollub]

(In [5991]) Reset slow-sync set to allow multiple syncs (multi-sync) with one initialized OSyncEngine. Slow-sync reset was always unclean and only got reseted after the next connect() call. Since slow-syncs now can be triggered even before a connect (e.g. hashtable deletion) things needed to get cleaned up. Since sync-done() function is the very last plugin call in a multi-sync the slow-sync state get rested there for OSyncClientProxy and OSyncClient.

refs #960

[dgollub]

(In [5992]) Introduce testcase to verify correct slow-sync once the hashtable gets deleted.

fixes #960