0.9.1-preview now available

## [0.9.1-preview] - 2019-8-8
### Fixed
- Fixed GC heap garbage being caused by triggered by event processing.
* This meant that every processing of input would trigger garbage being allocated on the managed heap. The culprit was a peculiarity in the C# compiler which caused a struct in `InputEventPtr.IsA` to be allocated on the heap.
- The bindings selection popup window will now show child controls matching the current action type even if the parent control does not match.
- Fixed `duration` values reported for Hold and Press interactions.
- DualShock 3 on macOS:
* Fixed actions bound to the dpad control performing correctly.
* Fixed non-present touchpad button control being triggered incorrectly.
- Fixed compile issues with switch classes on standalone Linux.
- Leak of unmanaged memory in `InputControlList`.
#### Actions
- Fixed actions not updating their set of controls when the usages of a device are changed.
- Composite bindings with the default interaction will now correctly cancel when the composite is released, even if there are multiple composite bindings on the action.
### Changed
- `MouseState`, `KeyboardState`, and `GamepadState` have been made public again.
- `PlayerInput` and `PlayerInputManager` have been moved from the `UnityEngine.InputSystem.PlayerInput` namespace to `UnityEngine.InputSystem`.
- The signature of `InputSystem.onEvent` has changed. The callback now takes a second argument which is the device the given event is sent to (null if there's no corresponding `InputDevice`).
```
// Before:
InputSystem.onEvent +=
eventPtr =>
{
var device = InputSystem.GetDeviceById(eventPtr.deviceId);
//...
};
// Now:
InputSystem.onEvent +=
(eventPtr, device) =>
{
//...
};
```
- The signatures of `InputSystem.onBeforeUpdate` and `InputSystem.onAfterUpdate` have changed. The callbacks no longer receive an `InputUpdateType` argument.
* Use `InputState.currentUpdateType` in case you need to know the type of update being run.
- `InputUpdateType` has been moved to the `UnityEngine.InputSystem.LowLevel` namespace.
- `InputSystem.Update(InputUpdateType)` has been removed from the public API.
- The way input devices are built internally has been streamlined.
* `InputDeviceBuilder` is now internal. It is no longer necessary to access it to look up child controls. Simply use `InputControl.GetChildControl` instead.
* To build a device without adding it to the system, call the newly added `InputDevice.Build` method.
```
InputDevice.Build<Mouse>();
```
* `InputSystem.SetLayoutVariant` has been removed. Layout variants can no longer be set retroactively but must be decided on as part of device creation.
- `InputSystem.RegisterControlProcessor` has been renamed to just `InputSystem.RegisterProcessor`.
#### Actions
* `InputAction.ReadValue<TValue>()` is longer correlated to `InputAction.triggered`. It simply returns the current value of a bound control or composite while the action is being interacted with.
* `InputInteractionContext.PerformedAndGoBackToWaiting` has been renamed to just `InputInteractionContext.Performed`.
#### Actions
- Individual composite part bindings can now no longer have interactions assigned to them as that never made any sense.
### Added
- Devices can now have more than one usage.
* Call `InputSystem.AddDeviceUsage(device,usage)` to add additional usages to a device.
* Call `InputSystem.RemoveDeviceUsage(device,usage)` to remove existing usages from a device.
* `InputSystem.SetDeviceUsage(device,usage)` still exists. It will clear all existing usages from the given device.
- A new `VisualizerSamples` sample that can be installed through the package manager.
* Contains two components `InputControlVisualizer` and `InputActionVisualizer` that help visualizing/debugging control/device and action activity through in-game overlays. A few sample scenes illustrate how to use them.
#### Actions
- Added `InputAction.ReadValueAsObject` API.
- Added `InputAction.activeControl` API.