It compiles. It sorta works. Several subcommands are FIXME marked and
broken, because things that used to accept separate --backend and --key
params need to be changed to accept just a --key that encodes all the key
info, now that there is metadata in keys.
Moved away from a map of flags to storing config directly in the AnnexState
structure. Got rid of most accessor functions in Annex.
This allowed supporting multiple --exclude flags.
