Back to being only [crowdfunded](https://patreon.com/joeyh) now.

Several little things today, including a git-annex.cabal patch from
fftehnik that fixed building without the assistant, and supporting
`AWS_SESSION_TOKEN`. The main work was on making `git annex drop --dead`
prune obsolete per-remote metadata, and on fixing a bug in v6 mode that
left git-annex object files writable.

Today's work was sponsored by Paul Walmsley in honor of Mark Phillips.
