node to page: Make Nodes into Pages

* `.Site.Pages` now contains all page types, including sections etc.
* `.Data.Pages` will also contain "node type" pages where relevant.

Updates #2297

hugolib/hugo_sites_build.go

@@ -156,7 +156,7 @@ func (h *HugoSites) assemble(config *BuildCfg) error {
 		}
 	}
 
-	if err := h.createMissingNodes(); err != nil {
+	if err := h.createMissingPages(); err != nil {
 		return err
 	}