hgcia: access status fields by name rather than index

context: store status class instead of plain tuple in self._status This improves readability a bit by allowing us to refer to statuses by name rather than index.

status: update and move documentation of status types to status class The various status types are currently documented on the dirstate.status() method. Now that we have a class for the status types, it makese sense to document the status types there instead. Only leave the bits related to lookup/unsure in the status() method documentation.

status: update various other methods to return new class

status: create class for status lists Callers of various status() methods (on dirstate, context, repo) get a tuple of 7 elements, where each element is a list of files. This results in lots of uses of indexes where names would be much more readable. For example, "status.ignored" seems clearer than "status[4]" [1]. So, let's introduce a simple named tuple containing the 7 status fields: modified, added, removed, deleted, unknown, ignored, clean. This patch introduces the class and updates the status methods to return instances of it. Later patches will update the callers. [1] Did you even notice that it should have been "status[5]"? (tweaked by mpm to introduce the class in scmutil and only change one user)

lfutil: avoid creating unnecessary copy of status tuple In lfdirstatestatus(), the status tuple gets deconstructed, the lists get updated, and then an identical status tuple gets created and returned. Change it so we simply return the original tuple.

dirstate: separate 'lookup' status field from others The status tuple returned from dirstate.status() has an additional field compared to the other status tuples: lookup/unsure. This field is just an optimization and not something most callers care about (they want the resolved value of 'modified' or 'clean'). To prepare for a single future status type, let's separate out the 'lookup' field from the rest by having dirstate.status() return a pair: (lookup, status).

commit: update file nodeid and flags in the same place Now that we have a separate variable for the original 'm1' manifest, we can safely update the nodeid of the file in the new manifest in the same place as we update the flags.

commit: use separate variable for p1 manifest and new manifest In localrepo.commitctx(), p1's manifest is copied and used as the basis for the manifest that is about to be committed. The way the copy is updated makes it safe to use it where the original p1's manifest is wanted. For readability, though, a separate variable for each purpose would be clearer. Make it so.

commit: remove dead initialization of 'lock' The 'lock' variable is initialized to None, but before it's ever read, it's assigned again.