v0.5.0-a5

Added

• Alphabet.__eq__ implementation comparing letters.
• pool argument to pyopal.align to support reusing a ThreadPool.

Changed

• Update Aligner.align to use the BaseDatabase Cython API.

Fixed

• Memory leak in Aligner.align caused by faulty allocation of pointer array.
• __repr__ implementations of Alphabet and FullResult.
• Alphabet.__getitem__ reading past the letters buffer.