Add auto-generated list of special node types to editor documentation

- Click one to jump directly to the description of that node.
- Back/forward buttons work thanks to history API.
- List is sorted alphabetically.
- This was also done for the page describing item abilities.

doc/editor/appendix/nav.js

@@ -0,0 +1,41 @@
+/*
+	Gathers <dt> elements and builds a list of links to them.
+*/
+
+document.addEventListener('DOMContentLoaded', function() {
+	var elems = document.querySelectorAll('.autolink > dt');
+	var links = []
+	for(var i = 0; i < elems.length; i++) {
+		var li = document.createElement('li');
+		links.push(li);
+		var name = elems[i].innerHTML;
+		name = name.split(/\s*[:-]\s+/);
+		name = name[1] || name[0]
+		li.innerHTML = name;
+		li.addEventListener('click', (function(n) {
+			return function() {
+				//var newloc = Object.create(location)
+				//newloc.search = "jumpto=" + n;
+				history.pushState(null, null, "?jumpto=" + n);
+				elems[n].scrollIntoView(true);
+			};
+		})(i));
+	}
+	links.sort(function(a,b) {
+		if(a.innerHTML < b.innerHTML)
+			return -1;
+		if(a.innerHTML > b.innerHTML)
+			return 1;
+		return 0;
+	});
+	document.querySelector('.navbar').insertAdjacentHTML('beforeend',"<h2>Jump to:</h2>");
+	var nav = document.createElement('ul');
+	nav.classList.add('nav-jump');
+	for(var i = 0; i < links.length; i++)
+		nav.appendChild(links[i]);
+	document.querySelector('.navbar').appendChild(nav);
+	// Now check if one was requested in the query string
+	var dest = location.search.match(/^jumpto\=(\d)/, '');
+	if(dest && dest[1] >= 0 && dest[1] < elems.length)
+		elems[dest].scrollIntoView();
+});