wireproto: use decorator for the batch command

wireproto: add decorator for wire protocol command Move move in the same direction we took for command line commands. each wire protocol function will be decorated with its name and arguments. Beside beside easier to read, this open the road to easily adding more metadata (like security level or return type)

wireproto: drop the _decompress method in favor a new call type We already have multiple call function for multiple return type. The `_decompress` function is only used for http and seems like a layer violation. We drop it in favor of a new call type dedicated to "stream that may be useful to compress".

wireproto: document protocol specific function of wirepeer Those function are explicitly declared and documented now.

wireproto: introduce an abstractserverproto class sshserver and webproto now inherit from an abstractserverproto class. This class is introduced for documentation purpose.

wireproto: document possible return type The wireprotocole command use a small set of class as return value. We document the meaning of each of them. AS my knowledge of wire protocol is fairly shallow, the documentation can probably use improvement. But this is a better than nothing.

pull: add a set of steps that remain to be done during the pull With bundle2 we'll slowly move current steps into a single bundle2 building and call (changegroup, phases, obsmarkers, bookmarks). But we need to keep the old methods around for servers that do not support bundle2. So we introduce this set of steps that remains to be done.

pull: put discovery step in its own function The discovery is a full step that will grow to contain more than changesets. We set it in its own function like all other steps.

pull: move the cgresult logic in _pullchangeset Logical follow up of the previous changeset. The `_pullchangeset` is now responsible of setting the `pullop.cgresult`.

pull: move return code in the pull operation object With bundle2 we'll have multiple code path susceptible to be responsible for adding changeset during the pull. We move it to the pull operation to simplify this the coming logic. The one doing the adding the changegroup will set the value.

merge: use ancestor filename from planning phase instead of filectx ancestor test-merge-types.t changes a bit in flag merging. It relied on the implementation detail that 100% identical revlog entries are reused. The revlog reuse did that fctx.ancestor() saw an ancestor where there really not was one.

tests: prevent test-hup from hanging forever if the transaction does not start If the transaction fails to start because of some programing errors, the test would stay stuck in this while loop forever. We now added a basic safeguard that abort the loop if nothing happen in 10 seconds. 10 seconds sounds enough to let the server catch up and open a transaction.