To get direct access to the code, please refer to the git and github documentation.
The source code in the FieldTrip toolbox is split over multiple directories reflecting the modular organization. The modular organization facilitates a separation between end-user functions that also do data bookkeeping, and low level functions that focus on the algorithms.
For many of the tools (github, wiki, mailman, twitter, facebook) that we use we have made an integration, e.g. an update on the wiki is automatically tweeted.