Upgrade core library version 0.82.1 -> 0.82.2

This release of core fixes some query issues. For further details, see https://github.com/Tightdb/tightdb/blob/master/release_notes.md#0822-release-notes.

I have updated `CHANGELOG.txt`, but I have only added this:

Updating to core library version 0.82.2

I'll let you guys decide on what additional details to add.