v0.6.0

• Dropped support for Python versions 2.6, 3.2 and 3.3
• Added support and testing for Python 3.7
• Optimized the n-grams Levenshtein search for long sub-sequences
• Further optimized the n-grams Levenshtein search
• Cython versions of the optimized parts of the n-grams Levenshtein search