Boostbook: Merge from trunk.

- Template parameter documentation.
- Don't print an empty table/hr in header if there is not image or
  navigation info.
- Initial mathjax support.


[SVN r75947]

tools/boostbook

@@ -1 +1 @@
-Subproject commit 453cea92dc9442a35cdbdc171d92d5e19a9ae5c4
+Subproject commit b684ebaa7ceba8cffe9bee6ff88c109932fff5bb