Back to being only crowdfunded 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.