PEP-8 compliance

Mostly by running:

autopep8 --in-place . --max-line-length 160 -r

This fixes #4, and also fixes #6.

doc/source/quickstart.rst

@@ -18,7 +18,7 @@ Quick start
     >>> del m['a_sample_key']
     >>> print(m.keys())
     ['other_key']
-    
+
 The contents of the dictionary are stored to disk. For example, in another python interpreter:
 
 ::
@@ -27,7 +27,7 @@ The contents of the dictionary are stored to disk. For example, in another pytho
     >>> m = mmapdict('/tmp/test.mmdpickle')
     >>> print(m['other_key'])
     [1, 2, 3]
-    
+
 
 It is also possible to open the file in read-only mode, in which case any modification will fail:
 
@@ -42,29 +42,29 @@ It is also possible to open the file in read-only mode, in which case any modifi
         raise io.UnsupportedOperation('not writable')
     io.UnsupportedOperation: not writable
 
-    
+
 Of course, the main interest is to store numpy arrays:
 
 ::
 
     >>> import numpy as np
     >>> from mmappickle.dict import mmapdict
     >>> m = mmapdict('/tmp/test.mmdpickle')
-    >>> m['test'] = np.array([1,2,3],dtype=np.uint8)
+    >>> m['test'] = np.array([1,2,3], dtype=np.uint8)
     >>> m['test'][1] = 4
     >>> print(m['test'])
     [1 4 3]
     >>> print(type(m['test']))
     <class 'numpy.core.memmap.memmap'>
-    
+
 As you can see, the ``m['test']`` is now memory-mapped. This means that its content is not loaded in memory, but instead accessed directly from the file.
 
 Unfortunately, the array has to exist in order to serialize it to the ``mmapdict``. If the array exceed the available memory, this won't work. Instead one should use stubs:
 
 ::
 
     >>> from mmappickle.stubs import EmptyNDArray
-    >>> m['test_large']=EmptyNDArray((300,300,300))
+    >>> m['test_large'] = EmptyNDArray((300,300,300))
     >>> print(type(m['test_large']))
     <class 'numpy.core.memmap.memmap'>
 
@@ -78,7 +78,7 @@ Finally, one last useful trick is the :meth:`mmappickle.mmapdict.vacuum` method.
     >>> #Here, /tmp/test.mmdpickle still occupies ~216M of hard disk
     >>> m.vacuum()
     >>> #Now the disk space has been reclaimed.
-    
+
 .. warning ::
 
     When running :meth:`mmappickle.mmapdict.vacuum`, it is crucial that there are no other references to the file content, either in this process or in other.