Merge branch 'receive-pack-filter'

* receive-pack-filter:
  ReceivePack: Clarify the check reachable option
  ReceivePack: Micro-optimize object lookup when checking connectivity
  ReceivePack: Correct type of not provided object
  IndexPack: Tighten up new and base object bookkeeping
  ReceivePack: Remove need new,base object id properties
  ReceivePack: Discard IndexPack as soon as possible
  ReceivePack: fix ensureProvidedObjectsVisible on thin packs

Change-Id: I4ef2fcb931f3219872e0519abfcee220191d5133