Add ws_event_new to header
Add ws_event_new to event.c
Merge pull request #359 from xVin/add-ws_event_new

[WIP] Add ws event new
Add missing free() call in ws_event_new
Merge pull request #360 from xVin/fix-ws_event_new

Add missing free() call in ws_event_new
Add set_select_lowest to header
Add implementation of ws_set_select_lowest()
Add interface def. for ws_set_select_greatest()
Implement ws_set_select_greatest()
Merge pull request #363 from matthiasbeyer/add-set_greatest_lowest

Implement ws_set_select_greatest/lowest()
Add extensive documentation about the hotkey subsystem
Add file for hotkey DAG implementation
Add interface definitions and stubs for DAG
Add initial hotkey event type
Add function for retrieving the next DAG node
Implement insertion function for the DAG
Add initial setup for hotkey subsystem
Add event handling function
Add preliminary implementation of deinitialization