Add support for content-only flag when rendering pages

[gmarull]

Support for pages was added in #596. This PR adds support for the content-only flag when rendering pages, so that when creating an rst file with only

.. doxygenpage: test
    :content-only:

the entire page is rendered as if it was a native rst page.

Note that this is my first contribution to breathe, so expect a non-optimal/wrong solution. Suggestions are welcome :-)

[carlescufi]

cc @utzig

[utzig]

LGTM. One interesting change is that adding :content-only: creates a new section with the title from the \page element, which IMO is correct and was not done previously. Would be interesting to eventually also update non :content-only: to also add this section.

[utzig]

LGTM. One interesting change is that adding :content-only: creates a new section with the title from the \page element, which IMO is correct and was not done previously. Would be interesting to eventually also update non :content-only: to also add this section.

Btw, I tested a previously fetched version from a few days ago and missed that you force pushed a change, so now it seems you made it consistent without the title; I personally liked the version that had the title extracted from the \page, although having the same behavior with or without the setting seems like a better solution.

[gmarull]

@utzig the reason I removed title inclusion is because in some occasions, it is helpful to include content between title and the actual content, e.g. to insert a toctree to reference doxygen subpages and so create the same tree structure as in doxygen.

[gmarull]

@vermeeren can you review? thanks

[gmarull]

@michaeljones can you review? thanks

[vermeeren]

@gmarull (and others) I should be able to get to all pending reviews and issues this week, some unexpected events ended up taking a significant amount of time in the past month.

[vermeeren]

@gmarull Looks good, thanks for the patches!