magit-key-mode-popup-committing: support --author option
magit-wash-diffstat: split regex to make it easier on humans

This is just in preparation to make it longer.
magit-wash-diffstat: support binary files

Binary files are displayed with "Bin XXX -> YYY bytes" instead of the
change count and graph. The numbers correspond to the old and new sizes
of the binary file, not lines added/removed, hence the capture groups
for these are left empty and this text left with no special faces.
Merge pull request #1253 from afrepues/fix/truncated-diffstat-with-binary-files

Fix truncated diffstat with binary files
magit-ellipsis: use #x2026 for "horizontal ellipsis"

to avoid encoding problems.  Close #1249.
magit-with-emacsclient: use --socket-name even with default server-name

When actually using a socket for communication, then always pass the
`--socket-name' argument to the Emacsclient.  Do so even when neither
the `server-name' nor `server-socket-dir' have been set to something
different from the default values.

Just because a user did not configure Emacs to use something else,
doesn't necessarily mean that she did not attempt to so, but stopped
after making adjustments to shell init files.  I.e. there are users
with incomplete configurations, who gave up on using the Emacsclient
after having shot themselves in the foot by incompletely configuring
client/server communication.  Magit requires cannot do without the
Emacsclient and so we have to override such mistakes.