Don't snap pcolor
TST : test `plot(.., color='none')`

added failing test for issue #2760
BUG : make `plot(..., color='none')` work again

Fixes #2760

Fixes miss-handling of color conversion logic introduced in edc48f0
Merge pull request #2761 from tacaswell/fix_line_color_handling

Fix line color handling
Make it possible to control snapping from the outside.
Merge pull request #2726 from mdboom/pcolorsnap

Don't snap pcolor
changed the text of INSTALL to be correct about what external
dependencies you need to install on windows.
TST : eventplot empty event list

test for eventplot not raising an exception
BUG : allows empty event lists to be passed in

fixes #2786
Merge pull request #2787 from tacaswell/empty_event_loop

Empty eventplot.
Merge pull request #2774 from tacaswell/windows_installdoc_tweak

Changed the text of INSTALL to be correct about external dependencies for Windows.
BUG: Fixes the string character for XDG message.
Merge pull request #2799 from pelson/XDG_message_repr

Xdg message repr
ENH: Updated inset locator axes to return a HostAxes by default
BLD: Python 3 requires method definition flags to include METH_VARARGS when setting METH_KEYWORDS
DOC: specified the keys of the dictionaries returned by cbook.boxplot_stats
DOC: formatted key-value list as a table and added some latex math
BUG: stop_event_loop method should have flags METH_NOARGS as it has no arguments
DOC: point downloads at the matplotlib downloads
Merge pull request #2821 from matthew-brett/fix-download-link

DOC: point downloads at the matplotlib downloads