Bring the names of various boxes closer to spec language. This should
hopefully make things easier to understand and hack on. :^)
Some notable changes:
- LayoutNode -> Layout::Node
- LayoutBox -> Layout::Box
- LayoutBlock -> Layout::BlockBox
- LayoutReplaced -> Layout::ReplacedBox
- LayoutDocument -> Layout::InitialContainingBlockBox
- LayoutText -> Layout::TextNode
- LayoutInline -> Layout::InlineNode
Note that this is not strictly a "box tree" as we also hang inline/text
nodes in the same tree, and they don't generate boxes. (Instead, they
contribute line box fragments to their containing block!)
Now the functions can actually be demonstrated by small examples,
embedded right inside the documentation via:
spreadsheet://example/<page>#<example_name>
Also allows pages to link to each other via the same scheme:
spreadsheet://doc/<page>
In a few places I also simplified a few format strings:
-outln("{} item{}", items, items.size() == 1 ? ' ' : 's');
+outln("{} item(s)", items);
In my opinion this is more readable and in some places it incorrectly
wrote '0 item' which is "fixed" now. In other places the placeholder
space looked weird.
