fixed variable name
(cherry picked from commit 19c80a83a2819bdac73dfe4bc08e270205a9a666)
Add support for mail sending via msmtp

(adapted cherry-pick from commit 7f8b9b6e2fb49ce3bae166674a06754e5940ea04 of Dosenpfand)
Some little modifications and additions in the doc of the config file
Add the --restore-dir synonym and update the documentation accordingly
Complete the half-done work of previous commit
Minor typo correction to the README file
Merged https://github.com/zertrin/duplicity-backup.git

Conflicts (straight-forward resolution):
	README.md
Merge pull request #57 from piperj/pull

Minor typo correction to the README file
Merge remote-tracking branch 'upstream/master' into merge