dirstate-entry: add a `state` property (and use it) This replace the [0] access. Ultimately is we should probably get ride of this in its current form. However this is a good transitional solution to move away for tuple indexing for now. Differential Revision: https://phab.mercurial-scm.org/D10954

dirstate: move most of the `remove` logic with dirstatemap `removefile` This code deal with special logic to preserving "merged" and "from_p2" information when removing a file. These are implementation details that are more suitable for the dirstatemap layer. Since the dirstatemap layer alreaday have most of the information necessary to do so, the move is easy. This move helps us to encapsulate more implementation details within the dirstatemap and its entry. Easing the use of a different storage for dirstate v2. Differential Revision: https://phab.mercurial-scm.org/D10953

dirstate: add a `in_merge` property This factor the "p2 is not null" check and is fairly simpler to read. Differential Revision: https://phab.mercurial-scm.org/D10952