Upgrade core library version 0.81.0 -> 0.82.0
Updates necessitated by change core Group API (https://github.com/Tightdb/tightdb/pull/515)
Update changelog
Fix crash when adding an object already in a realm to another realm
Upgrade core library version 0.82.0 -> 0.82.1
Don't set TIGHTDB_MAX_LIST_SIZE for debug builds
Merge pull request #831 from realm/ks-use-core-ver-0.82.1

Upgrade core library version 0.82.0 -> 0.82.1