phabricator: add the uploadfile function This is needed to be able to submit binary files such as images in commits (and also non-UTF-8 text files). One of the primary disadvantages of the current use of createrawdiff is that Phabricator simply drops any binary diffs included in the patch, but not the files, so if such a diff is then committed it corrupts any binary files in it. Differential Revision: https://phab.mercurial-scm.org/D7047

phabricator: add the uploadchunks function Differential Revision: https://phab.mercurial-scm.org/D7046

phabricator: add the maketext function This add the diff data for a text file to a phabchange. Differential Revision: https://phab.mercurial-scm.org/D7045

phabricator: add the phabdiff data structure This holds all the data about a commit, and is passed to the differential.creatediff API. Differential Revision: https://phab.mercurial-scm.org/D7044

phabricator: add the phabchange data structure These store data about individual files in a commit. Differential Revision: https://phab.mercurial-scm.org/D7043

phabricator: add the phabhunk data structure These store the actual diff data (for UTF-8 text files anyway) and are equivalent to hunks in a patch file. Differential Revision: https://phab.mercurial-scm.org/D7042

phabricator: add the DiffChangeType and DiffFileType constants These are used in Phabricator change objects. There are more values but so far as I can tell we don't need them. Differential Revision: https://phab.mercurial-scm.org/D7041

help: adding a help category to narrow and remotefilelog commands Differential Revision: https://phab.mercurial-scm.org/D6998

rust-cpython: drop self.borrow_mut() in favor of PySharedRef wrapper

rust-cpython: drop self.leak_immutable() in favor of PySharedRef wrapper

rust-cpython: add safe wrapper representing shared data borrowed from PyObject PySharedRef is a tempoary wrapper around PySharedRefCell. It provides safe functions for each shared data. $shared_accessor implements a safe method to construct PySharedRefCell. This allows us to add more than once PySharedRefCell to a Python object.

rust-cpython: move $leaked struct out of macro It wasn't easy to hack the $leaked struct since errors in macro would generate lots of compile errors. Let's make it a plain struct so we can easily extend it. PyLeakedRef keeps a more generic PyObject instead of the $name struct since it no longer has to call any specific methods implemented by the $name class. $leaked parameter in py_shared_iterator!() is kept for future change.