Disable pull-to-refresh when remote search is not allowed

Fixed issue 6151
Restore instance state in correct order

Fixes issue 5968
Support extras for ACTION_VIEW + mailto: URI

Support the extras documented for ACTION_SEND to be used with
ACTION_VIEW to support another app that doesn't care, namely Twitter.
Alternative fix for issue 5697 - ASUS display bug
Don't crash when startActivity() fails

Fixes issue 6201
Should disable COMPOSE menu item

When message viewing and tap the next icon, menu icons (previous, next, delete and replys) disappears for an instant.
But a compose icon remains, then tap it accidentally.
Fix 'endless' loop in ImapFolderPusher

Under certain circumstances it's possible that the 'push state' isn't
updated to contain the most recent 'UIDNEXT' value. In that case
ImapFolderPusher.start() would execute the same code path through its
main loop over and over again, preventing the device from going to
sleep.
Rather than changing the code to update the 'push state' in the corner
case that triggers the behavior described above, this commit introduces
another mechanism to track the 'UIDNEXT' value. This should also catch
as of yet unknown cases where the 'push state' isn't properly updated.

At some point in the future I hope we get to a point where we only
persist the 'push state' when we manually stop/restart the service.
During normal operation there's no need to read from/write to storage
all the time.

Fixes issue 4907
Add mailbox.org to list of providers
Avoid adding the same recipient twice when using "reply to all"

Fixes issue 6056
Fix sendCommand line splitup for some imap proxys

When sending a command it would be sent like this:
PKG1: 1 STARTTLS
PKG2: \r\n

Some imap proxys (maybe from Fortinet?) don't accept commands across packets:
PKG1: 1 STARTTLS\r\n
Exclude error folder from unread/starred count
Avoid NullPointerException reported via Google Play
Fix potential ClassCastException

Implemented the fix suggested by zjw in pull request #463
https://github.com/k9mail/k-9/pull/463

Fixes issue 5928
Add missing import
Update changelog for 4.804