D422: mdiff: add a --ignore-space-at-eol option

[yuja (Yuya Nishihara)]

yuja added inline comments.

INLINE COMMENTS

> morisgi wrote in cmdutil.py:126-127
> Regular diff chose -Z for the short option

`-Z` sounds good, which doesn't conflict with any existing short
options.

FWIW, the long option is called as `--ignore-trailing-space` in
GNU diff.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D422

To: dsp, #hg-reviewers, quark
Cc: yuja, morisgi, akushner, martinvonz, quark, mercurial-devel