DOC: fix code-block ipython highlighting

[jorisvandenbossche]

I noticed some warnings in the travis doc build log in the sense of "WARNING: Could not parse literal_block as "python". highlighting skipped."
This was because some of the .. code-block:: python directives contained code that could not be interpreted as python. And, additionally, these code blocks were also not highlighted correctly (the In [1] prompt were not recognized by the default python highlighter).

Therefore, I changed those .. code-block:: python directives containing IPython prompt to .. code-block:: ipython

[jreback]

oh, this fixes it great!

[jorisvandenbossche]

Fixed the merge conflict.

So in the future, when using a code-block that includes some IPython In []/Out [] prompts, we should use ipython, and otherwise python is OK (although actually in that case you can also use just :: as python is the default)

[jreback]

@jorisvandenbossche lgtm.