Enlighten

**Changes**
- Output will now be resized on the first write after a resize is detected
- This addresses an issue that can cause threaded programs to crash 28
- Default Unicode are now used when running under Windows Terminal
- Other windows terminals, like CMD, will still default to cp65001 compatible characters

**Bug fixes**'
- Additional stream flushes added to ensure incidental flush aren't relied upon 21
- Updated RPM installation instructions

**Changes**
* Warning is now emitted when a reserved field is passed as a user-defined field
* Drop Python 2.6 support
* Begin testing 3.10-dev

**Bug fixes**
* Preserve max scroll offset when number of status bars decrease (27)
* Minor doc fixes

**New Features**
- Status bars can now be created with [Manager.status_bar()](https://python-enlighten.readthedocs.io/en/stable/api.html#enlighten.Manager.status_bar)
- Bars can now be [invoked](https://python-enlighten.readthedocs.io/en/stable/api.html#enlighten.Manager.counter) with ``autorefresh=True`` to trigger a refresh whenever another bar is updated or refreshed
- ``fill`` can now be used multiple times in counters and status bars
- Remaining space is divided equally
- Fill character can now be specified for [counters](https://python-enlighten.readthedocs.io/en/stable/api.html#enlighten.Counter), with ``fill`` keyword
- Compound colors, like ``'aqua_on_seagreen'`` are now supported
- Additional keywords passed to [Counter()](https://python-enlighten.readthedocs.io/en/stable/api.html#enlighten.Counter) and [Counter.update()](https://python-enlighten.readthedocs.io/en/stable/api.html#enlighten.Counter.update) are now used as [user-defined fields](https://python-enlighten.readthedocs.io/en/stable/patterns.html#user-defined-fields)

**Changes**
- ``Counter.last_update`` is now updated when [Counter.refresh()](https://python-enlighten.readthedocs.io/en/stable/api.html#enlighten.Counter.refresh) is called
- ``Counter.last_update`` is now reset when [Counter.clear()](https://python-enlighten.readthedocs.io/en/stable/api.html#enlighten.Counter.clear) is called

**Bug fixes**
- Position pinning now works as expected

Bug Fixes:
- Ensure scroll reset does not exceed screen height 19

Housekeeping:
- Updated [documentation](https://python-enlighten.readthedocs.io/en/stable/examples.html#color) to provide colored text examples

Bug Fixes:
- Fix Read The Docs references that point to latest
- Support counter tests in non-Unicode environments
- Account for unsupported encoding value when determining default series

New Features:
- Support for RGB and X11 [colors](https://python-enlighten.readthedocs.io/en/latest/api.html#series-color)
- New parameter for [Counter()](https://python-enlighten.readthedocs.io/en/latest/api.html#enlighten.Counter): `additional_fields`
- User-defined fields available for counter [formatting](https://python-enlighten.readthedocs.io/en/latest/api.html#counter-format)
- New multiprocessing [example](https://github.com/Rockhopper-Technologies/enlighten/blob/master/examples/multiprocessing_queues.py)
- Subcounter fields `count_n` and `rate_n` are now available in counter-only [format](https://python-enlighten.readthedocs.io/en/latest/api.html#counter-format)
- New repr output

Bug Fixes:
- Fallback series for non-unicode encoding 13
- Workaround implemented for Python 3.9 Issue [39966](https://bugs.python.org/issue39966)

Changes:
- Drop EL6-specific testing
- Python 2.6 automated testing is still enabled, but failures are non-blocking
- Specifying [color](https://python-enlighten.readthedocs.io/en/latest/api.html#series-color) by index is now deprecated
- Minimum supported version of [Blessed](https://pypi.org/project/blessed/) is [1.17.2](https://github.com/jquast/blessed/releases/tag/1.17.2)

Housekeeping:
- Added Python 3.9-dev testing