store: refactor the fncache handling
put all the fncache file writing and reading in
the same place.
adding dir/baradding foodir/barfoocommitted changeset 0:d44511117907adding dir/bar_2adding foo_2dir/bar_2foo_2committed changeset 1:a85812e0561aadding aadding cremoving aadding bremoving cadding drecording removal of a as rename to b (100% similar)