* fix unit test after thread-sorting change (fixes #413)
* don't mark the mail-header-separator as read-only

  this seems to cause problems in some cases, where message-mode
  apparently requires the text to be writable.
* make mu4e-view-url-regexp a public variable

  thus, users can more easily experiment with this
* mu4e: add fallback for `delete-all-overlays'
* mu4e: don't add rogue \n where re-editing
lib/mu-str.c: squash white space ctrl chars to spaces

When processing multiple lines for a subject line separated by TAB
characters we don't want to eliminate the control character totally but
replace it with a simple space. I've left the control handling as before
for non-white space characters.

Signed-off-by: Alex Bennée <alex@bennee.com>
Merge pull request #422 from stsquad/remove-ctrl-squash-space

* lib/mu-str.c: squash white space ctrl chars to spaces (#390)
* Merge branch 'master' of github.com:djcb/mu
* mu: shell-quote rather than escape with --exec
Avoid sorting by nil
Merge pull request #429 from sabof/default-to-descending

* mure: headers sorted by "nil" at first; avoid this.
* mu4e: some doc updates
* mu4e: unbreak address display, removing toggling