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

DOC/MNT : Freetype isn't actually optional
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)
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.
Fix for all backends
Add comment
Merge pull request #3826 from mdboom/path_collection_optimization_crash

Don't do draw_marker optimization for large paths
Merge pull request #3846 from ariejdl/master

BUG : fix typo in base-class MathtextBackend

ABC has class that is never over-ridden by sub-classes and never used, renamed to the method used by sub-classes.
Merge pull request #3845 from mbyt/out_of_memory_access_as_strided

BUG: ensure integer shape, strides for as_strided
BUG/DOC : fix ciho -> cihi typo

Closes #3775
Merge pull request #3854 from tacaswell/BUG_cihi_typo

BUG/DOC : fix ciho -> cihi typo
Allow `color=None` to be passed to plotting functions.
Robustness and functionality for `color=None`.
Fixed PEP8 issue with spacing between function arguments.
Added test for giving `color=None` to plot function.