v0.0.3

Improved control-action binding model

Input devices generate input events for their controls, where a
"control" is the physical button/stick/mechanism that actually generated
the event.

ControlManagers bind actions to these controls, and any input events for
that control will be tagged with the action. The engine can then filter
the input event stream by action to get the relevant input events. This
decouples device controls from engine actions, which makes it easier to
later implement control remapping.

v0.0.2

WIP input system

v0.0.1

Build script improvements