Syncing strategy

[Sebastian Spaeth]

I am looking into our syncing algorithm and plan to provide patches that
document it better, and also tweaks the logic (still need my test suite
before that).

I have a couple of questions about our policy in certain situations:

- Currently when we blow away/corrupt the LocalStatus files, the next
  run will basically ignore the local Maildir and resync from the IMAP
  to the local Maildir. Is that the intented behavior that we want to
  keep (basically blowing away our local Maildir)?

- If we modify e.g. flags both on the Local and on the remote side, the
  local side will currently override whatever has been changed on the
  remote side. Do we want it this way?

Finally, our current strategy is to go though all folders and syncing
local changes to the remote server. After finishing we go through all
folders again and sync remote changes to the local side. I don't know if
plenty of IMAP "SELECT" statements hurt us performance-wise. 

I think it would make sense to sync in both directions while we have an
IMAP connection to a folder anyway. Especially with lots of folders, it
*might* be a performance win (it wouldn't hurt in any case). More
importantly, in case offlineimap is interrupted, we would have more
folders already synced in a complete (ie 2-way sync) way, rather than
having all of them synced only in one direction.
Would people be interested in such a change?

Sebastian