This module is responsible for providing the backbone for the rest of the packages when it comes to the features of Cactus.
The main difference between this and the cactus-common package is that this one
does not guarantee it's features to work in the browser.
The main difference from the cactus-core-api package is that this is meant to
contain actual implementations while cactus-core-api is meant to be strictly
about defining interfaces. Based on that latter constraint we may move the
PluginRegistry out of that package and into this one in the near future.
// TODO: DEMONSTRATE API