* mu4e: allow mu4e-html2text-command to be a function (thanks to tmalsburg)
* mu4e: make the faces a bit more generic
* mu4e: small improvement in mu4e-headers-found-hook defcustom
* mu4e-draft: small faces update
Merge pull request #300 from thierryvolpiatto/master

* fix empty buffer when replying and prevent user calling a new update when one is already running.
* mu4e: restore the old update-buffer behaviour
* mu4e: fix faces in the mu4e-main
* mu4e: some improvements in the update-mail window behaviour (wip)
* mu4e: some more work on the updating process