Merge commit 'egit/zawir/corechanges'
* commit 'egit/zawir/corechanges':
Add PackIndex specific tests, currently only iterators tests
Entries iterator in PackIndex and indirectly PackFile
Add getObjectCount() method to PackFile
Add size() method to ObjectIdSubclassMap
Copying constructor of MutableObjectId
Add overload of fromRaw() in MutableObjectId accepting int[]
Move PackFile.SIGNATURE to Constants.PACK_SIGNATURE
Replace instanceof in WalkFetchConnection with getType()
Add getType() method to RevObject hierarchy
Format PackIndexV1 class
Format PackIndex class
Format PackFile class