When converting ghost keys to Blender's event system:
- All keys that aren't part of the GHOST_TKey enum map to EVENT_NONE
(ignored), note that it's an internal error if the value of key isn't
a known value.
- Modify the switch statement so any missing members of GHOST_TKey
warn at compile time (GCC & Clang only).
- GHOST_kKeyUnknown maps to EVT_UNKNOWNKEY.
We could ignore this key, changing can be evaluated separately.
f634010c6e