As screwed up by e1dcbebb

add docs that when completions are object they can have a from: and to:
that will be used by pick.

Make sidebar in manual scrollable for small screen especially usefull
when `Programming API` is unfolded

seem to look nice on Chrome and Firefox Osx, (scrollbar do not appear,
except when scrolling on Chrome) but should maybe be tested on linux.

HTML5 tag parsing hack, and invert css media query.

Woah, IE still defaults to a border around images in links.

Add docs for first-class document features, split API section
into subsections to make it easier to read.

Closes #878

This was especially noticeable with non-default font-sizes. The wrapper div and additional pre are required due to using the font-size provided by the browser (using em throughout).

So that I can put other doc-related stuff there without polluting the
root dir.