Deltachat

- fix python bindings to use core for copying attachments to blobdir
and fix core to actually do it. hpk42

- trigger reconnect more often on imap error states. Should fix an
issue observed when trying to empty a folder. hpk42

- un-split qr tests: we fixed qr-securejoin protocol flakiness
last weeks. hpk42

- fix grpid-determination from in-reply-to and references headers. hpk42

- only send Autocrypt-gossip headers on encrypted messages. dignifiedquire

- fix reply-to-encrypted message to also be encrypted. hpk42

- remove last unsafe code from dc_receive_imf :) hpk42

- add experimental new dc_chat_get_info_json FFI/API so that desktop devs
can play with using it. jikstra

- fix encoding of subjects and attachment-filenames hpk42
dignifiedquire .

- historic: we now use the mailparse crate and lettre-email to generate mime
messages. This got rid of mmime completely, the C2rust generated port of the libetpan
mime-parse -- IOW 22KLocs of cumbersome code removed! see
https://github.com/deltachat/deltachat-core-rust/pull/904#issuecomment-561163330
many thanks dignifiedquire for making everybody's life easier
and jonhoo (from rust-imap fame) for suggesting to use the mailparse crate :)

- lots of improvements and better error handling in many rust modules
thanks link2xt flub r10s, hpk42 and dignifiedquire

- r10s introduced a new device chat which has an initial
welcome message. See
https://c.delta.chat/classdc__context__t.html#a1a2aad98bd23c1d21ee42374e241f389
for the main new FFI-API.

- fix moving self-sent messages, thanks r10s, flub, hpk42

- fix flakiness/sometimes-failing verified/join-protocols,
thanks flub, r10s, hpk42

- fix reply-to-encrypted message to keep encryption

- new DC_EVENT_SECUREJOIN_MEMBER_ADDED event

- many little fixes and rustifications (link2xt, flub, hpk42)

- now uses async-email/async-imap as the new base
which makes imap-idle interruptible and thus fixes
several issues around the imap thread being in zombie state .
thanks dignifiedquire, hpk42 and link2xt.

- fixes imap-protocol parsing bugs that lead to infinitely
repeated crashing while trying to receive messages with
a subject that contained non-utf8. thanks link2xt

- fixed logic to find encryption subkey -- previously
delta chat would use the primary key for encryption
(which works with RSA but not ECC). thanks link2xt

- introduce a new device chat where core and UIs can
add "device" messages. Android uses it for an initial
welcome message. thanks r10s

- fix time smearing (when two message are virtually send
in the same second, there would be misbehaviour because
we didn't persist smeared time). thanks r10s

- fix double-dotted extensions like .html.zip or .tar.gz
to not mangle them when creating blobfiles. thanks flub

- fix backup/exports where the wrong sql file would be modified,
leading to problems when exporting twice. thanks hpk42

- several other little fixes and improvements

- fix location-streaming 782

- fix display of messages that could not be decrypted 785

- fix smtp MAILER-DAEMON bug 786

- fix a logging of durations 783

- add more error logging 779

- do not panic on some bad utf-8 mime 776