Fix #1799: path collections with NaNs in the path cause exceptions in vector backends.
Merge pull request #1799 from mdboom/issue1799

Corrupt/invalid PDF and EPS files when saving a logscaled plot made with negative values
Fix the clippath renderering so that it uses no-clip unsigned chars
typo, break lines >80 char, add link to cmaps list

some lines with links extended past 80 char, broke them up, which shouldn't affect the links.
BF - prevent a TypeError for lists of vertices
Merge pull request #1854 from ajdawson/bugfix-marker-list

BF - prevent a TypeError for lists of vertices
fill_betweenx signature fixed
Fix issue #1844 in custom_scale_example.py
The rcParam lines.marker should not be used for gridlines
Add a test
Add test
Merge pull request #1846 from mdboom/agg-clip-rendering-fix

Fix the clippath renderering so that it uses no-clip unsigned chars
Merge pull request #1796 from mdboom/gridline-markers

axes.grid lines using lines.marker settings?
Merge remote-tracking branch 'upstream/v1.2.x'

Conflicts:
	lib/matplotlib/tests/baseline_images/test_axes/polar_axes.pdf
	lib/matplotlib/tests/baseline_images/test_axes/polar_axes.png
	lib/matplotlib/tests/baseline_images/test_axes/polar_axes.svg
	lib/matplotlib/tests/baseline_images/test_axes/single_point.pdf
	lib/matplotlib/tests/baseline_images/test_axes/single_point.png
	lib/matplotlib/tests/baseline_images/test_axes/single_point.svg
	lib/matplotlib/tests/test_axes.py
	src/_backend_agg.cpp