hg-core: remove the `Operation` trait
There is no way to currently define a trait which can both return references
to `self` and to passed data, which is what we would need.
Generic Associated Types may fix this and allow us to have a unified interface.
See: rust #44265
Differential Revision: https://phab.mercurial-scm.org/D8862
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.