Merge: nitweb: add READMEs summaries

Automatically add a summary extracted from the README / doc contents

![image](https://cloud.githubusercontent.com/assets/583144/20892633/fef2fd4a-badc-11e6-89f5-5de007981914.png)

Also add anchors to the content of the README, so you can make links like:

http://nitweb.moz-code.org/doc/core#Methods-Implicitly-Defined-in-Sys

Pull-Request: #2342

diff --cc share/nitweb/javascripts/nitweb.js
Simple merge

diff --cc share/nitweb/stylesheets/nitweb.css
Simple merge