Bring our SSH config parser up-to-date with respect to changes in
OpenSSH. In particular, they fixed[1] the handling of line comments
such that #-characters inside strings are not considered. This means
that we have to parse strings with escaped quotes correctly.
[1] https://bugzilla.mindrot.org/show_bug.cgi?id=3288
Change-Id: Ifbd9014127e8d51e7c8792e237f3fc2a9a0719d2
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>