Merge: nitdoc: fix things, add more tests and benches

Merge: nitdoc: fix things, add more tests and benches

Two fixes:

* no more multiple instanciation of ToolContext (-25% of total nitdoc time)
* fixed JS scripts (no more bug with the search bar that does not display)

Testing:
* add more tests on pages structure
* add a script to build the documentation from origin/master version (easier to diff outputed doc after local changes)
* add a benchmark to nitdoc against the origin/master version

Performances comparison after fix on ToolContext:

![image](https://cloud.githubusercontent.com/assets/583144/8042382/e9feba6c-0dec-11e5-9bf9-0a3806209ee9.png)

(`CI-nitdoc` is busy right now on Jenkins so you will have to wait for the demo)

Pull-Request: #1446
Reviewed-by: Jean Privat <jean@pryen.org>