* Add experimental mouse API
* Add aurora::core library for aurora::ms
* Add absl::flat_hash_map library for aurora::ms
* Add comment clarifying MS is an aurora extension
* Clear MSStatus::buttons to prevent spurious values
* Minor cleanup for MSRead and MS_BUTTON_* bits
* Switch to Poll -> Read paradigm
* Clear mouse scroll state before polling for events
If we try and initialize anything controller related before the event
subsystem is initialized we lose all controllers detected on startup.
To solve this we simply wait until the first frame is about to be rendered
*then* initialize the controller subsystems