Features update to version 0.9.7

- Added RELEASES file (still updating to bring it current).
- High water-mark, timestamps and return num_entries when writing to ets_buffers.
- Stacktraces in failed cxy_ctl spawns
- Allow process dictionary partial or full migration to newly spawned cxy_ctl processes
- Change API for cxy_ctl to include init, add/remove task types, and adjust task limits