Update JSON files from master branch of masterfiles.
Build JSON files for 3.7 content.
Hashes on right hand side of library elements to avoid double-linkage.
Support level 4 in the left navigation
Experimental - remove base_url
Merge pull request #113 from dmitry84/master

support 4 level in the left navigation and remve base_url
Use a regular expression to try to detect unresolved links.

The naive grep'ing for ][ produces too many false positives from
code blocks using arrays.
Autocommit: libraries changed 2014-06-17-12:14:35