Add extensive documentation about the hotkey subsystem
Add initial hotkey event type
Add (de)initializing functions
Add file for hotkey DAG implementation
Add interface definitions and stubs for DAG
Add function for retrieving the next DAG node
Add implementation of insertion function for the DAG
Add preliminary implementation of deinitialization
Add implementation of event removing function
Add initial setup for hotkey subsystem
Add event handling function
Add functions to add and remove events to hotkeys
Add logging to hotkeys subsystem