no-delete-local patch for offlineimap

[Petr Fischer]

Hello!

is possible to add this useful patch for "no-delete-local" option to the official offlineimap release?
It's usefull and simple. Users of offlineimap sometimes want this feature (found on internet, forums etc.).

This is not my patch, it's patch from some github fork.

https://github.com/OfflineIMAP/offlineimap/commit/266c88f7a1b041ba169e0c0cab767bf412c23672

pf