fix last commit
magit-blame-format-time-string: fix by removing 95%

The removed code failed in multiple places and as result all times
not in GMT got corrupted.  Replace it with a oneliner.  Also rename
`magit-time-format-string' to `magit-blame-time-format', and change
its default value, the old one was to noisy.
magit-locate-emacsclient: quote value

Also remove an unused variable.
Merge branch 'master' into next

Conflicts:
	magit.el
magit-commit-assert: allow empty merge commits
fix 526e9eb8dee4f3c220c4c9435cb1157ed1e506d3
magit-wash-hunk: parse stored heading as value
magit-visit-file: reuse existing window

When the file to be switched to is already visible in another
window of the current frame, then pop to that instead.
magit-hunk-file-position: new function

replacing `magit-hunk-target-line'.
magit-dired-jump: don't require dired-x

`dired-jump' is autoloaded, so we don't
need to explicitly require it before use.
magit-goto-section-hook: new variable
magit-{section,hunk}-set-window-start: new functions

Add `magit-hunk-set-window-start' to `magit-goto-section-hook'.
Maybe these functions are good enough, or maybe we need something
more elaborate.