v0.2.0

This is the second release of igor for general consumption. This igor release
is still marked as a pre-release. I have used igor to manage my dotfiles for
some time now, with only a smaller bug (encoding issues for templated files)
that was fixed in cd97ff4 and thus is fixed within this release. With the
addition of vaults, Igor currently seems to be feature-complete for my current
usecase. Igor now has a small set of active users which did not report major
issues with me either, so I would consider it stable enough for the casual
user. Hopefully, after some more field-testing, the next release will then be
an actual stable-relese. Bug-reports welcome.