Include number of messages in a thread in number of selected messages

Selecting a placeholder message will select all messages in its thread.
Remove unused method
Don't create (throw-away) Message objects when starting action mode
Delete all messages in a thread when 'delete' is used on the placeholder
Fix computeBatchDirection()
Fix deleteThreadsSynchronous()
Retain selected messages when message list is reloaded
Make flag operations work on all messages in a thread
Group messages by account when moving to spam/archive folder
Avoid converting lists to arrays when possible
Javadoc cleanup
Clean up method copyOrMove()
Copy/move all messages in a thread when copying/moving placeholder
Should change Bcc address when Identity changed.
Removed unused column from projection
Make the message selection code use the unique (Cursor) ID
Merge branch 'master' into content_provider

Conflicts:
	src/com/fsck/k9/activity/MessageList.java
	src/com/fsck/k9/fragment/MessageListFragment.java
Updated Japanese translation. catch up with 952c407.
Slightly better whitespace symmetry in the messagelist
Clean up the icons in account list