Loadconfig

* Add library write_file
* Add namespaces to Config.run
* Improve library exc and add last and Ret. Add tests and cleanup
* Improve version parsing
* dev version update

* Update clg dependency
* Simplify package version handling
* Make tempdir and tempfile library functions more generic
* Improve handling of default cli command
* Add new Run Popen subclass that can be used as context manager. Add async
mode, handle output as utf-8, improve string splitting when not using
subshell and use process sessions to handle subprocesses. Refactor run
library function
* Add Config.render functionality expanding Config in a string
* Add default command clg keyword. Update tests and docs
* dev version update

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* Remove six dependency
* Simplify API adding version and prog. Update tests and docs
* Refactor argparse_clg patch to simplify SystemExit interface. Update tests
and docs
* Refactor README.rst to make Pypi happy

* Make README.rst more github compatible.
* Add yaml file loading capability with new !read tag. Expand docs.
Add README.rst badges. Add Config run functionality. Improve tests
* Make get_version library function more generic. Add first and improve run
lib functions
* Refactor yaml Config methods. Make Config return empty string on None
* Remove six dependency when pip installing from sources
* Improve Pypi classification
* Get docs version from setup.cfg

* Add yaml !env environment variables to config
* Significantly improve testing and debugging with pytest. Refactor and add
new tests using pytest. Add new odict tests. Make key expansion more robust.
Expand $ keys within -C arguments. Flatten lists on config export. Multiple
library improvements

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* docs: Ensure docs can be built on readthedocs