Related changes:
- Moved all non-ASCII symbols into `segment_data`
- Added --config_path, replaced nargs='*' with better action='append'
- Added g:powerline_config_path vim option
- Added ipython overrides (via additional arguments to setup() or c.Powerline)
TODO: support for non-string scalars in vim overrides.
Fixes#231
Modules can now be any string, and an informative error message will be
written to sys.stdout if the module doesn't exist. The
`last_pipe_status` argument will also automatically be split into
a list.
Support for unicode literals was reintroduced in Python 3.3 which makes
supporting both Python 2 and Python 3 much easier, so this will be the
minimum supported Python 3 version.
Closes#8.