Alter indentation
Make vim and ipython ext configurations optional
Add renderer docstrings.
Remove `pl` argument and first argument to `render*` from docs
Fix documentation for ThreadedSegment classes with @staticmethod’s
Rename PowerlineState to PowerlineLogger
Special-case None priority in place of -1

This extends priorities in both directions, uses slightly faster `is None`
check, makes it consistent with `interval` special-casing also to `None` and
makes lint able to use one simple `.type()` check in place of `.either()` one.
Use different default for functions

This makes it look up `powerline.segments.vim.virtualenv` in addition to
virtualenv in colorscheme like it does with `segment_data`.
Respect segment.py highlight group handling in powerline-lint

Either `highlight_group` or `name` key is enough to determine highlight group
for non-function segments, but powerline-lint requires `highlight_group`.
Move some code from powerline_autodoc to powerline.lib.inspect

To make it available later in lint checker.
Improve arguments checks
Improve shown errors
Do not sort segments that are always included
Do not use second argument to itertools.count
Do not use second argument to itertools.count in other place
Make tests more verbose and catch first KeyboardInterrupt
Improve generate_gradients tool

Changes:

- Port argument parsing to argparse
- Add weights support
- Add ability to specify cterm palette
- Purge out first 16 colors from color choosing by default
- Improve different scales and different preview length support
Use same modeline in scripts/* as in other files
Fix indentation of dictionaries
Add dark_GREEN_Orange_red gradient

Generated with

    ./tools/generate_gradients.py 22 58 94 52 --weights '60 15 10 2'
. For use in virtcol_current.