Add block to allow customizing html output prompt

[eddiejessup]

For generating HTML reports I usually want to completely hide cells' output, apart from a select few types such as HTML and images. I can almost accomplish this with a custom template inheriting from full.tpl, except that I can't hide the output prompt without hiding the cell output itself. I can if I add this block.

[takluyver]

Thanks, I think this is a reasonable addition.

Can you add it to the template structure doc, which is rendered at:
http://nbconvert.readthedocs.io/en/stable/customizing.html#Template-structure

[mpacer]

Should be good to go.

[takluyver]

I don't think this is quite right:

1. The new block goes before the output content blocks (like execute_result), not wrapping them.
2. The new block is only in the HTML template; there's a separate section below for extra blocks in the HTML template.

[eddiejessup]

Hey @michaelpacer, based on @takluyver's comments I dropped your commit, but thanks for helping out, I definitely wouldn't have noticed I needed to update the notebook otherwise!

@takluyver, I think the HTML structure is now correct. I wasn't sure how best to state the block inheritance, so I just went for an explicit {% super %}, hope this doesn't make the document show too much implementation guts. If you can think of a nicer way to express this, I'd be happy to change it.

[takluyver]

Thanks! I think {% super %} is too much implementation guts. Can we say something like 'output type as above'? There's already an 'as above' in the Latex section below. Better wording welcome.

[eddiejessup]

@takluyver thanks for the feedback! I think all done.

[takluyver]

Thanks :-)

[mpacer]

This may have broken rtd.

[eddiejessup]

@michaelpracer hey, sorry what's rtd mean?

[eddiejessup]

@michaelpacer

[mpacer]

Readthedocs I.e., http://nbconvert.readthedocs.io I got an email warning of its failure this morning and this is the pr that merged around then.

…

On Wed, Dec 28, 2016 at 10:42 Elliot Marsden ***@***.***> wrote: @michaelpacer <https://github.com/michaelpacer> — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#500 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ACXg6Mz0Yy_gIufLiGTdukexiw0BayiGks5rMq2PgaJpZM4LS7cX> .

[eddiejessup]

Thanks for catching this. I'm not familiar with how readthedocs works, where can I see its build details? I can see that it looks like the ipython notebook with the template structure is shown there, but the PR changes aren't reflected, even in its 'latest' version.

[takluyver]

I think Mike has got it working again, but for the record, you can see RTD build logs here: https://readthedocs.org/projects/nbconvert/builds/

[mpacer]

I think it ended up being independent of this PR per se (it was just what triggered the most recent failure), so no worries.