Change message when libpng pkg-config lookup fails
Merge pull request #1978 from mdboom/type42-python3

Setting font type using rcParams does not work under Python 3.*
Merge remote-tracking branch 'upstream/v1.2.x'
Fix bug in SpanSelector, introduced in commit #dd325759

The useblit attribute was being set after calling new_axes,
but new_axes needs that attribute.  By setting useblit before
calling new_axes, we set it based on the initial canvas; even
though new_axes might change to a different canvas, we assume
it will be the same type of canvas (same backend), so its
supports_blit attribute will not change.
Merge pull request #1982 from efiring/SpanSelector_blit_bug

Fix bug in SpanSelector, introduced in commit dd325759
Fix #1984: Use float for result of rgb_to_hsv
Updated test, and added a check for tuple length
Documenting the isRGB -> isRGBA change to API
Merge pull request #1984 from mdboom/rgb_to_hsv

colors.rgb_to_hsv does not work properly with array of int dtype
Fix #1985: Horizontal histograms are created with the wrong arguments
Merge pull request #1985 from mdboom/horizontal-histogram

horizontal histogramm doesn't work in 1.2 branch
Merge remote-tracking branch 'upstream/v1.2.x'

Conflicts:
	lib/matplotlib/axes.py
Go back to one ghostscript process per test
Fix some test images that weren't being run on Travis before
Run tests in parallel on Travis and in tox
Include all test files
Make the test function name match so that they can be pickled through multiprocessing
Don't call "show" from a test
Fix typo so correct gs executable will be run
Remove import of old util