Update README.md
Merge branch 'argparse' (into master)
Update login error
network: simplify imports and strip excess whitespace
network updates

* Remove unused (and non-working) async support
* Some more descriptive comments and variable names
Add UnsupportedPythonVersion
Add User-Agent header by default

Specifies username and framework, and will eventually specify a version other than "alpha"

Closes #6
make wikibot_samples.ui usable as a module
Add UserLoginAborted and slightly better exception handling