pull: gather all bookmark-pulling code together Pulling bookmarks is done in two rounds. First we do a simple update, then we use the content of the `bookmark` argument to possibly overwrite some bookmark with their remote location. The second step was not done right after the first one for some obscure reason. We now perform them one after the other.

push: perform bookmark export in the push function This part is responsible for adding new bookmarks on the remote. Before that, it was done on its own in `commands.push`. The export is still not integrated with the rest of the push process, but at least it now dwells in the right function.

push: add `pushoperation.bkresult` This attribute will be used to carry the result of the bookmark push (when the `push` function will effectively be doing any bookmarks pushes)

push: pass list of bookmark to `exchange.push` Currently stored but not unused. This parameter will control bookmarks explicitly pushed (added to the server if missing).

exchange: import bookmarks as bookmod Using the original names makes it difficult to use `bookmarks` as a variable name.

push: sanitize handling of bookmark push return value Mixing return and assignment does not make sense, let's unify this.

locarepo: remove the `push` method (API) All the logic of this function is in the exchange.push function for some time. We just stop calling `localrepo.push` in `command.push` to have access to more information. Leaving `localrepo.push` in place will let third-party extensions wrap it but it would never be called by `hg push` making the wrapping useless. Therefore, the method is removed so that third-party code fail noisily and get properly upgraded.

push: `exchange.push` instead of `localrepo.push` The latter is going away.

clone: use `exchange.push` instead of `localrepo.push` The latter is going away.

push: use `exchange.push` in `commands.push` To gain access to all results from the push, we need to have access to the `pushoperation` object. We call `exchange.push` to do so. It is impossible to just change the `localrepo.push` signature because the change may be too subtle to be caught by external extension wrapping `localrepo.push`. This mean we'll have to kill `localrepo.push` because just using `exchange.push` in `commands.py` would silently disable all wrapping around `localrepo.push` by third-party extensions. So we'll remove it in a later changeset to get such extensions to fail noisily.

push: `exchange.push` now returns the `pushoperation` object Returning the pushop object gives access to more information (upcoming bookmark push result for example). `localrepo.push` currently extracts the `cgresult` for callers.

push: rename `pushop.ret` to `pushop.cgresult` We are about to introduce more results-related attributes on pushop (for bookmarks) so we need a more distinctive name. We now use `cgresult` as `pulloperation` does.

obsolete: use version constants in the format mapping

obsolete: use the `version` argument in encodemarkers Recent scientific studies show that assigning a variable have no effect on a unrelated constant. We therefore use the variable where we intended to in the first place.

obsolete: gather all contents related to format version 0 in a single place All contents includes documentation, constants, and functions, so we gather all of those things into a single location. The diff is confusing because it cannot understand what code is semantically moved around in this grand migration.

revert: properly back up added files with local modification These files were previously not backed up because the backup mechanism was not smart enough. This leads to data lose for the user since uncommitted contents were discarded. We now properly move the modified version to <filename>.orig before deleting it. We have to use a small hack to do a different action if "--no-backup" is specified. This is needed because the backup process is actually a move (not a copy) so the file is already missing when we backup. The internet kitten is a bit disapointed about that, but such is life. This patch concludes the "lets refactor revert" phases. We can now open the "Lets find stupid bug with renames and merge" phases. I'm sure that now that the code is clearer we could do it in another simpler way, but I consider the current improvement good enough for now.