\li senf::console::DirectoryNode provides internal nodes with an arbitrary number of children
\li senf::console::CommandNode describes a command entry in the tree
+ \li senf::console::LinkNode is a link to another node. It works much like a symlink on POSIX
+ systems.
senf::console::CommandNode is the base-class of all command nodes of which there are several,
depending on the type of command.
\li A senf::console::CommandNode is normally added to the tree by directly adding a callback
using one of the overloaded senf::console::DirectoryNode::add() members. See \ref
console_commands.
+ \li A senf::console::LinkNode is created by senf::console::DirectoryNode::link()
When directly adding a node callback, the type of node added depends on the type of
callback. The callback types which can be added are listed at \ref console_callbacks.