bitstring-4.1.2

Another maintenance release. Once again some small changes to the 'beta' Array class,
plus new Array functionality.

• Fix for the module command-line usage. Bug #290.
• Fix for when creating bitstrings from memoryview objects.
• Renamed the 'fmt' parameter for Arrays to 'dtype'.
• More Array operator coverage.
• Added operators that act on two Arrays of the same size.
• Added comparison operators for Arrays that return an Array of bools.
• Added Array.equals method as == will now return an Array (see above item).
• Added astype() method for Arrays to easily cast to a new dtype.