Merge: nitweb: show mentities details

Add more content to mentities pages.

Packages list inner groups
* http://nitweb.moz-code.org/package/core

Groups show parent and list inner groups/modules
* http://nitweb.moz-code.org/group/core%3E
* http://nitweb.moz-code.org/group/core%3Ecollection%3E

Modules show imported modules, introduced classes and redefinitions
* http://nitweb.moz-code.org/module/core::array

Classes show super classes, introduced properties, redefined properties
* http://nitweb.moz-code.org/class/core::Array

Bonus, all lists are filterable by raw string or visibility.

Pull-Request: #2152
Reviewed-by: Jean Privat <jean@pryen.org>