prepare a fresh git checkout for doc build on MS windows
Updated whats new for nbagg and legend/patheffects docs.
Fix rotation in RegularPolyCollection
Previous matplotlib had a bug.  As per documentation, specifying empty
string for sym argument should prevent drawing fliers for boxplots.

As an example, the following script displays fliers in the boxplot
when it shouldn't.

    import matplotlib.pyplot as plt

    data = list(range(0,100)) + [200,-200,250,-250]
    bp = plt.boxplot(data,sym='',widths=.3)
    plt.show()

Added logic to ensure empty sym string does not display fliers.
MNT : minor refactor of patch from bmistree
BUG : Merge branch bxp_fliers_no_sym into v1.4.x

This is the code from PR #3573
Merge pull request #3409 from jbmohler/win_fixes

BLD/DOC : patch over git + symlink issues on windows
Add test
Merge pull request #3574 from mdboom/regular-polygon-rotation

BUG : `rotation` parameter had no effect on `RegularPolyCollection`
Merge pull request #3594 from wernerfb/UnicodeInitProblem

BUG : Unicode decode error on with unicode username on py2+win
Merge pull request #3560 from pelson/nbagg_whats_new

DOC : Updated whats new for nbagg and legend/patheffects docs.
Merge v1.4.x into master