obsolete: rename _fnodesize to _fmfnodesize All variables involved in the obsstore format are prefixed with `_fm`. `_fnodesize` was the exception. It is now back in line. This is meaningful as we'll need to distinguish between multiple versions of the obsstore format.

obsstore: have the `mergemarkers` method return the number of new markers The mergemarkers function now returns the number of unknown markers in the stream that have been added to the obsstore. This is similar to what `obsstore.add` already does. The method gains a docstring in the process.

merge with i18n

test-bundle2: add obsolescence information to be exchanged To introduce a bundle2 way to exchange obsolescence markers, we need to have some information available to exchange. Introduce markers relevant to changesets involved in the exchange. The new markers reference the changesets as successor nodes of clowny (nonexistent) hashes so that other than being exchanged they have no effect. We introduce them in two waves as push is expected to be smart about the number of markers it exchanges sooner than pull.

help: only call doc() when it is callable `hg help -k` on my machine was aborting because the hg-prompt extension was inserting a string and not a function into help.helptable and help was blindly calling it. This patch changes keyword searching to be more robust against unexpected types.

i18n-pt_BR: synchronized with 6a8b8efb0641