Simplify GitData models

+ Implement table of contents. Close #457
Fix a typo
Add Vagrant config
Remove the un-needed development server

Nobody actually uses it and Vargant is a much better solution.
Use a predefined php.ini

This allows us to set options like `display_errors`
Implement `link_to` field for HSS doc. values

Also, now the format @OBJECT<PROPERTY>[VALUE] can be used as a values
table value or as the value of the `link_to` field to link to a value
of a property.
Proper spacing for the scope table
Make the wiki breadcrub more specific.
Fix a PHP notice
Disable sendfile in NGINX
Add margin to HSS doc. tables
Merge branch 'develop'