Retro: add EnvironmentCommand back
Retro: define some property setters of Environment as protected
Retro : moved the definition of delegates used by Core out of its definition
Retro: Core implements Environment
Demo: Engine no more implements Environment
Retro: rename Memory.Type to MemoryType
Core: replace get_memory_data and get_memory_size with get_memory
Rumble: rename Rumble.Effect in RumbleEffect
Sensor: rename Sensor.Action in SensorAction, rename Sensor.Accelerometer in SensorAccelerometer
Camera: rename Camera.Buffer in CameraBuffer
Log: rename Log.Level in LogLevel
Performance: move the subtypes out of Performance
Environment: add several interfaces