Improve api.Category

* Load pages by default
* Add __contains__, __len__
Rewrite argument parser (using argparse)
Merge branch 'master' into api
Progress bars! (+ui.py)
Make parsing colors optional
Add indefinite progress bar, improve non-tty output
Simplify non-tty output for indefinite progress bars
Progress bars for bot tasks
Update error messages
Custom variable lookup in console
Merge branch 'master' into argparse
Progress bar samples
Merge branch 'master' into argparse
Check for colorama on Windows
Check for colorama on Windows
doc
Merge branch 'master' into api: api.Category updates
Fix Python compatibility issues with querystring encoding and decoding (Python 2 & 3)

Notably, saving pages with unicode characters now works again in Python 2
Merge branch 'master' into argparse
Allow arguments to be accessed with __getitem__