Rename remaining magit-diff-stash occurrences
magit-stash-create: Fix message
quiet byte-compiler
quiet byte-compiler on travis-ci
no longer bind magit-stage-all-confirm in tests
magit-tests.el: restore symmetry of status tests
magit-tests.el: cosmetics
Merge pull request #1542 from kyleam/complete-rename

Rename remaining magit-diff-stash occurrences
Merge pull request #1541 from kyleam/fix-stash-message

magit-stash-create: Fix message
magit-save-repository-buffers: fix error when not inside repo

Fixes #1540.
magit-filename: new face
remove unused magit-diff-section-for-diffstat
rename magit-diff-{highlight => paint}-whitespace
rename magit-{section-diff => diff-file}-header
rename magit-{section-region-siblings => region-sections}
replace magit-current-sections with magit-region-values

Add function `magit-region-values' replacing `magit-current-sections'.
Both functions take an optional TYPES argument and return nil if the
sections in the region don't match.  But while the old function returned
a list of section objects the new function returns a list of section
values.  And while the old function did fallback to a list consisting
only of the current section if the region only spanned one section or
wasn't in use, the new function simply returns nil.

Use `magit-region-values' in places where `magit-current-sections' or
`(magit-region-sections 'magit-section-value)' was previously used.
Drop `magit-region-sections' now unused KEY argument.
replace magit-current-section with magit-section-highlighted-sections

Replace the variable `magit-current-section' whose value was a single
section with `magit-section-highlighted-sections' whose value is a list
of sections.

Currently all sections are still highlighted using overlays and because
these overlays are stored in existing `magit-section-highlight-overlays',
we don't actually have to store all highlighted sections in the new
variable yet.

This commit makes it possible to use text-properties instead of overlays
to highlight diff sections, but that follows in a later commit.
make the current section part of the section selection

Until now only sections that had at least one character inside the
region were part of the section selection, and so the current section
usually wasn't part of the selection.

Commands that only know how to act on a single section simply ignore
the selection and instead act on the current section.  When the current
section wasn't considered part of the selection yet this was problematic
because users don't necessarily know which commands use the selection,
so they might select A and B, while point is on C and invoke a command
with the intention to do something with A and B but instead end up
having something done to C.  Now they would expect something to happen
with A and B, and it would only happen to B, which is much less
problematic.
magit-section-make-overlay: return the overlay
magit-face-remap-set-base: new function

We cannot use `face-remap-set-base' because it is broken at least in
24.3; first it turns the input into an atom and then it tries to get
the car of that.

This isn't just a copy of that function; our implementation is simpler
but doesn't attempt to deal with any possible input we won't be using,
then again it does not barf on any input.