beginnings of stylesheet support for text()

- new stylesheet() command to read/write styles
- new DEFAULT constant to control whether styles inherit from the
context's font/size/fill
- quick & dirty ‘xml’ parser to find style tags in strings and convert
them into attributedstrings
- also fixed the color() command which hadn't been rewired to use
self.Color yet
successfully generating attributed strings
moved the Text class
util updates

- permutation sugar via shuffled(), ordered(), and order()
- files() now has a case-insensitive option and expands leading tildes
in glob patterns
- moved adict out of sandbox and updated xdict docstrings
new homes for path_helpers
text() now uses the stylesheet-driven, shared typesetter

- desperately in need of refactoring, but compliance.py passes at least
- also made some tweaks to the Color class for better hex string
support and preparation for an optional `mode` arg in color/fill/stroke
calls
c-extensions cleanup no. 6

- added python wrappers for the c libraries and moved both to the .lib
package
- was able to simplify the sys.path chicanery in the root __init__.py
- moved script.py’s namespace-builder into the top-level module (though
the helper classes still need to move to export.py before it can be
removed).
- setup.py now uses the buildlibs.py script (as does the xcode project)
rather than creating the extensions itself.