Rename/copy detection - options/display improvement proposition

Hi,

I think that:

   1. git-status should accept -M<n> -C<n>, same as git-diff
   2. git-diff should have an option to omit diff for deleted files

1. git-status incorrectly recognizes some changes as copied, e.g.:

# Changes to be committed: # copied: SimpleMatcher.h -> BSlashMatcher.h # copied: SimpleMatcher.h -> StringMatcher.h # renamed: SimpleMatcher.h -> TabMatcher.h

(generally SimpleMatcher.h is recognized as being copied into many different headers)

git-diff shows similarity index 50-60%. git-diff -M80 -C80 correctly stops recognizing this as copies/renames.

I think git-status also should learn -M and -C, as it works the same way as git-diff with defaults.

2. git-diff does not show diff for copied files. But when a files is
removed, the diff is shown.

I think seeing what was deleted is sometimes useful, but sometimes it is not and just clutters the diff.