Deltachat

API changes
- `dc_contact_get_last_seen()` added 2823
- python: `Contact.last_seen` added 2823
- removed `DC_STR_NEWGROUPDRAFT`, we don't set draft after creating group anymore 2805

Changes
- python: add cutil.from_optional_dc_charpointer() 2824
- refactorings 2807 2822 2825

Changes
- python: add mypy support and some type hints 2809

Fixes
- do not disable ephemeral timer when downloading a message partially 2811
- apply existing ephemeral timer also to partially downloaded messages;
after full download, the ephemeral timer starts over 2811
- replace user-visible error on verification failure with warning;
the error is logged to the corresponding chat anyway 2808

Fixes
- add 'waiting for being added to the group' only for group-joins,
not for setup-contact 2797
- prioritize In-Reply-To: and References: headers over group IDs when assigning
messages to chats to fix incorrect assignment of Delta Chat replies to
classic email threads 2795

API changes
- `dc_get_last_error()` added 2788

Changes
- Optimize Autocrypt gossip 2743

Fixes
- fix permanently hiding of one-to-one chats after secure-join 2791

API Changes
- `dc_join_securejoin()` now always returns immediately;
the returned chat may not allow sending (`dc_chat_can_send()` returns false)
which may change as usual on `DC_EVENT_CHAT_MODIFIED` 2508 2767
- introduce multi-device-sync-messages;
as older cores display them as files in self-chat,
they are currently only sent if config option `send_sync_msgs` is set 2669
- add `DC_EVENT_SELFAVATAR_CHANGED` 2742

Changes
- use system DNS instead of google for MX queries 2780
- improve error logging 2758
- improve tests 2764 2781
- improve ci 2770
- refactorings 2677 2728 2740 2729 2766 2778

Fixes
- add Let's Encrypt certificate to core as it may be missing older devices 2752
- prioritize certificate setting from user over the one from provider-db 2749
- fix "QR process failed" error 2725
- do not update quota in endless loop 2726

API Changes
- download-on-demand added: `dc_msg_get_download_state()`, `dc_download_full_msg()`
and `download_limit` config option 2631 2696
- `dc_create_broadcast_list()` and chat type `DC_CHAT_TYPE_BROADCAST` added 2707 2722
- allow ui-specific configs using `ui.`-prefix in key (`dc_set_config(context, "ui.*", value)`) 2672
- new strings from `DC_STR_PARTIAL_DOWNLOAD_MSG_BODY`
to `DC_STR_PART_OF_TOTAL_USED` 2631 2694 2707 2723
- emit warnings and errors from account manager with account-id 0 2712

Changes
- notify about incoming contact requests 2690
- messages are marked as read on first read receipt 2699
- quota warning reappears after import, rewarning at 95% 2702
- lock strict TLS if certificate checks are automatic 2711
- always check certificates strictly when connecting over SOCKS5 in Automatic mode 2657
- `Accounts` is not cloneable anymore 2654 2658
- update chat/contact data only when there was no newer update 2642
- better detection of mailing list names 2665 2685
- log all decisions when applying ephemeral timer to chats 2679
- connectivity view now translatable 2694 2723
- improve Doxygen documentation 2647 2668 2684 2688 2705
- refactorings 2656 2659 2677 2673 2678 2675 2663 2692 2706
- update provider database 2618

Fixes
- ephemeral timer rollback protection 2693 2709
- recreate configured folders if they are deleted 2691
- ignore MDNs sent to self 2674
- recognize NDNs that put headers into "message/global-headers" part 2598
- avoid `dc_get_contacts()` returning duplicate contact ids 2591
- do not leak group names on forwarding messages 2719
- in case of smtp-errors, iterate over all addresses to fix ipv6/v4 problems 2720
- fix pkg-config file 2660
- fix "QR process failed" error 2725