Caspo

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- Migrate to Python 3
- Migrate to Clingo 5

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- Bugfix in strategies visualization
- Bugfix in graph compression
- Remove duplicates edges when reading a SIF file
- Adds --optimum argument in caspo learn
- Prints number of hyperedges in caspo learn
- Adds stats

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- Refactoring removing ZCA-based implementation
- Use clingo python module (tested with clingo 4.5.x)
- Re-design subcommands as learn, classify, design, predict, control, visualize, and test
- Generate default visualizations using matplotlib and seaborn
- Adds sphinx docs
- Use travis-ci for building conda packages for OS X and Linux
- Adds a Dockerfile