Fix SDL2 include paths
Handling SDL2 include more nicely so that static linking supports "SDL2/SDL.h" incude path (instead of requiring "SDL.h")
Memsetting event struct to zero to be absolutely sure there is no inconsistent data in it breaking things
Adding event trigger for unknown key events
Whoops, avoid breaking numeric keys
[examples] fix sound example for 0.4 API
Merge github.com:Cat-Ion/Blitwizard