clfilter: rename `unfilteredmeth` to `unfilteredmethod` As originally intended.

clfilter: fix a false positive in the test-obsolete.t We push between two repo which once filtered looks unrelated. Weakness in the current implementation allows this push to be done without -f. But later improvement with filtering will make this push fails for unrelatedness. However we want this push to fail for including bumped changeset. So we had a smaller push --force to make them related.

clfilter: ensure that filecache on localrepo is unfiltered All filecache usage on repo is for logic that should be unfiltered. The caches should be common to all filtered instances, and computation must be done unfiltered. A dedicated storecache subclass is created for this purpose.