Fixed a problem with evaluating indented lines in pure python code.

:meth:`EmbeddedSphinxShell.process_pure_python` could not process
block of code with indentation correctly. For example, the following

.. ipython:: python

   for i in range(10):
       if i < 5:
           continue
       else:
           pass

would result in two IPython lines:

In [19]: for i in range(10):
   ....:      if i < 5:
   ....:          continue
   ....:

In [20]: else:
   ....:          pass
   ....:

This would raise various types of error, indentation/snytax, etc.

To resolve this problem, added a simple check for indentation
in the next line which normally start a new IPython line.

docs/sphinxext/ipython_directive.py

@@ -496,6 +496,12 b' class EmbeddedSphinxShell(object):'
             else: # still on a multiline
                 modified = u'%s %s' % (continuation, line)
                 output.append(modified)
+
+                # if the next line is indented, it should be part of multiline
+                if len(content) > lineno + 1:
+                    nextline = content[lineno + 1]
+                    if len(nextline) - len(nextline.lstrip()) > 3:
+                        continue
                 try:
                     mod = ast.parse(
                             '\n'.join(content[multiline_start:lineno+1]))