fix --from overriding annex-ignore

Make git-annex get/copy/move --from foo override configuration of
remote.foo.annex-ignore, as documented.

This already worked for remotes supporting hasKeyCheap. For others though,
git-annex copy --from foo would silently not do anything, while
git-annex copy --to foo would use the annex-ignored remote.

Also improved the annex-ignore docs, to reflect that `git-annex get`
without --from will skip using annex-ignored remotes, for example.

Sponsored-by: Dartmouth College's DANDI project

Command/Get.hs

@@ -87,7 +87,8 @@ perform key afile = stopUnless (getKey key afile) $
 {- Try to find a copy of the file in one of the remotes,
  - and copy it to here. -}
 getKey :: Key -> AssociatedFile -> Annex Bool
-getKey key afile = getKey' key afile =<< Remote.keyPossibilities key
+getKey key afile = getKey' key afile
+	=<< Remote.keyPossibilities (Remote.IncludeIgnored False) key
 
 getKey' :: Key -> AssociatedFile -> [Remote] -> Annex Bool
 getKey' key afile = dispatch