Add libsodium (Cryptography), RapidJSON (JSON), GStreamer (Multimedia), ...

...and massage some other items.

Item massaging done:
* Rename Asio to Boost.Asio, and also add it to Asynchronous Event Loop since it fits great.
* Improve V8 description with more text from their website, and since JSC isn't as prominent anymore.
* Categorize some items from the Etc. section.
* Alphabetic sorting of items within sections.