implement the context management protocol

You can now use the with statement:
  with pyaardvark.open() as a:
    a.configure()
	...

Signed-off-by: Michael Walle <michael.walle@kontron.com>
update 32-bit module to version 5.14

Signed-off-by: Michael Walle <michael.walle@kontron.com>
docs: update docstrings

Signed-off-by: Michael Walle <michael.walle@kontron.com>