improve(ScreenRobot): Implement adapters for Awt, Glass and JavaFX robots.

This PR implements adapters for several robots available in the APIs of Java and JavaFX; these are:

- `AwtRobotAdapter` for `java.awt.Robot` and `java.awt.MouseInfo`,
- `GlassRobotAdapter` for `com.sun.glass.ui.Robot` and
- `JavafxRobotAdapter` for `com.sun.javafx.robot.FXRobot`.

Their methods provide functionality for the robot lifecycle (prefixed with `robot`), keyboard input (prefixed with `key`), mouse input (prefixed with `mouse`), screen capturing (prefixed with `screen`) and timing (prefixed with `timer`). These methods accept parameters from the JavaFX API.

The `ScreenRobotImpl` was refactored to use `AwtRobotAdapter` and most of the functionality is implemented in `GlassRobotAdapter` and `JavafxRobotAdapter`.

It lays the foundation for headless testing using Monocle (it should be easy to exchange functionality from `AwtRobotAdapter` to `GlassRobotAdapter`) and bug fixes related to the `TypeRobot` (using the functionality of typing Unicode characters via JavaFX events from `JavafxRobotAdapter`).

cc: #92