pwstrorage: naieve password storage backend autodetection

this should probably be replaced with something a little
more intelligent at some point in the future.
atrous: cleanup presets

most of these presets represent subtler or stronger versions, that
can be achieved by mixing to 0.5 or 2.0

naming was slightly adjusted to get better (alphabetic) sorting
OSX packaging: minor change to make-app-bundle
Merge branch 'master' of https://github.com/darktable-org/darktable