group visual fixes

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Merge pull request #2276 from mcginty/group-meta-colors

group visual fixes
Fix for old-skool SMS key exchange UI behavior.

Also fixes SMS "end session" messages failing to end session.

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Bitmap OOM and rotation fixes

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media preview orientation

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Updated language translations

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Remove empty strings.

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Save drafts for recipients without an existing thread

- Prevent drafts without thread in database
- Clear drafts when deleting conversation(s), otherwise
  the drafts stay in the database and will reappear when a thread
  with the same threadId is created
- create separate SaveDraftTask class