Pre-release: Version 1.0.0a4

Enhancements continue in preparation for initial release of version 1.0.0.

Changes:

• Refactored to separate problems and problem interface from the algorithm itself
• Improved documentation
• Added iteration over Populations
• Added pretty-printing of Populations
• Improved version tracking mechanism

The package has been made available as a wheel on pypi and can be installed with pip using the command pip install xcs. It can also be downloaded directly from the python package index.