rust-revlog: add a Rust-only `InnerRevlog`
This mirrors the Python `InnerRevlog` and will be used in a future patch
to replace said Python implementation. This allows us to start doing more
things in pure Rust, in particular reading and writing operations.
A lot of changes have to be introduced all at once, it wouldn't be very
useful to separate this patch IMO since all of them are either interlocked
or only useful with the rest.
Mercurial
=========
Mercurial is a fast, easy to use, distributed revision control tool
for software developers.
Basic install::
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
Running without installing::
$ make local # build for inplace usage
$ ./hg --version # should show the latest version
See https://mercurial-scm.org/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.
Notes for packagers
===================
Mercurial ships a copy of the python-zstandard sources. This is used to
provide support for zstd compression and decompression functionality. The
module is not intended to be replaced by the plain python-zstandard nor
is it intended to use a system zstd library. Patches can result in hard
to diagnose errors and are explicitly discouraged as unsupported
configuration.