Make "hg incoming -r revision_number" work for remote repos (issue566) Uses the remote repository's lookup method as pull does and only transfers what is needed to calculate incoming changesets. One minor problem: As only the needed changesets are transfered and stored in a local bundle repository, the tip tag of this bundle is shows despite not being the tip changeset of the remote repository. (see "+tag: tip" in tests/test-incoming-outgoing.out in this patch)

Corrected similarity parameter used in test-addremove 0.5 meant 50% in the early stages of addremove -s, now 50 has to be used.

addremove: comparing two empty files caused ZeroDivisionError (found by Giorgos Keramidas)