Merge pull request #3754 from mdboom/freetype-not-optional

DOC/MNT : Freetype isn't actually optional
Add legend.facecolor and edgecolor to rcParams.
Tweak legend colors in ggplot style file.
validate_color can accept and return None
legend.facecolor and edgecolor default to None
legend.facecolor/edgecolor described in whats_new
legend updates in matplotlibrc.template
pep8 error: too many blank lines in legend.py
Merge pull request #3808 from tacaswell/colorbar_norm_bug

BUG : fix #3805
Fix tight bounding box calculation in axes-free figure
Merge pull request #3802 from mdboom/issue3802

BUG : Imsave AssertionError (empty bboxes)
BUG : changed default values of legend.*color -> None
TST : added tests for legend.*color rcparams
Avoid draw_marker optimization on large paths

Fix #3626
Just create the collection directly
MNT : add guard to not look up HOME env on windows

This variable should not be defined on windows so don't
even bother looking at it.

addresses #3804
Merge pull request #3829 from tacaswell/HOME_win32_guard

MNT : add guard to not look up HOME env on windows
Fix mixed mode renderer so it has width and height properties.
backend_wx: delete remaining lines for removal of printer support

This just finishes off the process; most of the removal was done
in #84ffb60.
Merge pull request #3839 from efiring/wx_printer_last_deletion

backend_wx: delete remaining lines for removal of printer support