Implement nav tweaks.

* Change colors in nav drawer
* Rename "Settings" to "More"
* Move "Log out" to "More" menu
* Add About page with version info and feedback
* Add search bar button to show ToC
* Update verbiage of "read in other languages"
* Make search bar persist on top, unless it's a low-res device

Change-Id: I581e0ded7aa7018828b9bb5cde879178a5e49cb1