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 implementation of deinitialization
Add implementation of event removing function
Add testing setup
Add CMakeLists setup
Add test for getting node from empty node
Add test for tree traversing
Add test for ws_dag_event_init
Add test for multiple inserts
Add test trying to remove event from empty node
Add test for insert-traverse-remove-traverse
Add test for initialization of ws_hotkey_event

Checks for duplicate code
Merge pull request #340 from neithernut/add-input_event_dag

Add input event DAG