mu4e: add custom variable for list of visible header flags - take 2
support recursive maildirs
support recursive maildirs
Merge branch 'recursive_maildirs' of https://github.com/nicolasavru/mu into recursive_maildirs

rebase to master
Merge pull request #178 from nicolasavru/recursive_maildirs

* improved recursive maildir support
Merge pull request #180 from abend/master

Customize visible header flags take 2.1
* mu4e:	small cleanup
* mu-contacts: convert the domain part of ascii-domains to lowercase
* mu-msg: initialize potentially uninitialized var
* mu-str: fix potential leak
* mu-store-priv: when rebuilding, remove the contacts-cache file, too
* cosmetic
* mu: provide fake-msgids for messages without; this fixes the problem where e.g. draft messages
  were not visible when using --include-related
* mu: handle addresses thay go beyond xapian's max term length (fixes issue #183)
  (we truncate them)
* update NEWS
* mu4e: copy address at point with c / C-u c in message-view
* mu4e: allow starting mu4e in the background
* mu4e: add background-starting to the FAQ
* mu-msg-part: don't free wrapper, we don't own it
* mu: mu-config: fix small leak