Merge branch '0.3.5-maintainance-tmpfile-suffix'
add mailto-helper
forward attached files in inline forwarding mode
properly wrap a forwarded message in message/rfc822 part
Move email_as_string function from crypto to helper module

The email_as_string function, and the related RFC3156_canonicalize
function, are now used by the ForwardCommand and are not specific
anymore to the crypto routine. So we move them to the global helper
module.
Merge branch '0.3.5-fix-forwards-682' into testing

Conflicts:
	alot/helper.py