* Replaced all from ...py23 import * with explicit name imports, or removed completely when possible.
* Replaced tounicode() with tostr()
* Changed all BytesIO ans StringIO imports to from io import ..., replaced all UnicodeIO with StringIO.
* Replaced all unichr() with chr()
* Misc minor tweaks and fixes
Some SVG authoring tool write arc commands without any space or comma around the boolean 'large-arc' and 'sweep' flags, leading our svg path parser to choke.
This makes the path parser smarter by special-casing arc command parsing so that it only consumes one character ('0' or '1') for these special boolean flags.
Implement the arc to curve points calculation using the original
svg.path library and use the curve points for the pen.
The Arc class and methods to parameterize and get curve points are
copied.
This makes the svg to glif conversion possible for any SVGs.
