xdiff: remove xemit related logic
xemit handles "diff formatting and output" with options like context lines,
whether show function names, etc. That is handled more cleanly at a higher
level in hg.
Removing context line parameters would also make the trimming logic (D2686)
cleaner and more confident. See [1].
[1]: https://github.com/git/git/commit/d2f82950a9226ae1102a7a97f03440a4bf8c6c09
Differential Revision: https://phab.mercurial-scm.org/D2705
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.