REL: v2.0.0b2

Second beta for v2.0.0

- fixed bugs in scaling dash pattern by linewidth
- fixed over/under propagating in images
- back ported improved png API from master
- deprecate gtk, gdk, wx (not gtkagg, wxagg) backends
- tweaks to default font sizes
- ensure default ticker always has at least 2 ticks
- remove vendored version of `six`
- updated GUI icons
- many small bug fixes
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2

iQEwBAABCAAaBQJXhd4yExx0Y2Fzd2VsbEBnbWFpbC5jb20ACgkQV/pFQN1O/Pe/
rggAjK3FpbLEJAPqkqm0QWTwrbMb2fFoVJ0s7zjakXl+QVWkATT/qLaz27AjkbPG
uytbsKuOukU4aGaR+PaW5pMMNdrbvIc+GV0nJPnKKU7A204C8g2M9BSdQKQkuoIi
9Zaa0nmsggBoEwKutiMFcsUZnACW8hJCvqM3Lx8Qzm6Vd6+x38DwhaaSL+sz4+5I
k3MTUXU3bkO+UlsjUamZfTxJ1TqR9pzw1fI3DWSl6Q4OFOeOcyby0IO58uK+fAdv
gVZVsE/W/68p8f9x8Mg7WVlWsEi1TFaaX79twJHifNbCH22adcxJ39UevGDPaykx
jTIpTjGxO5i8wGjOMS89jrVgDw==
=03fm
-----END PGP SIGNATURE-----