Before, it was shown by UI when the chat is empty, however, in case of
verified groups, this is never the case any longer as the 'e2ee now
guaranteed' is always added.
This is needed to test periodic re-gossiping in existing chats.
Also add a test for verified groups on that even if "member added" message is missed by a device of
newly added member, after re-gossiping Autocrypt keys to the group it successfully learns these keys
and marks other members as verified.
1:1 chat may be blocked while the contact is not
if 1:1 chat was created as a result of scanning
a verified group join QR code with the contact
as the inviter. In this case 1:1 chat is blocked to hide it
while the contact is unblocked.
It can be used e.g. as a default in the file saving dialog. Also display the original filename in
the message info. For these purposes add Param::Filename in addition to Param::File and use it as an
attachment filename in sent emails.
Opening the same account (context) from multiple processes is dangerous, can result in duplicate
downloads of the same message etc. Same for account manager, attempts to modify the same
accounts.toml even if done atomically with may result in corrupted files as atomic replacement
procedure does not expect that multiple processes may write to the same temporary file.
accounts.toml cannot be used as a lockfile because it is replaced during atomic update. Therefore, a
new file next to accounts.toml is needed to prevent starting second account manager in the same
directory.
But iOS needs to be able to open accounts from multiple processes at the same time. This is required
as the "share-to-DC extension" is a separate process by iOS design -- this process may or may not be
started while the main app is running. Accounts are not altered however by this extension, so let's
add to the `Accounts::new()` constructor an `rdwr` parameter which allows to read the accounts
config w/o locking the lockfile.
Webxdc update messages may contain
long lines that get hard-wrapped
and may corrupt JSON if the message
is not encrypted.
base64-encode the update part
to avoid hard wrapping.
This is not necessary for encrypted
messages, but does not introduce
size overhead as OpenPGP messages
are compressed.
The test checks that if webxdc update is too large to
download with the current `download_limit`,
it is applied afterwards when the user manually downloads the update message.
