Added HotkeyRegistration and InputEmulator interfaces

src/model/HotkeyRegistration.java

+package model;
+
+public interface HotkeyRegistration {
+    /**
+     * Registers a given hotkey.
+     * @param hotkey The hotkey to be registered. Must contain a unique ID.
+     * @return If the registration was successful.
+     */
+    boolean registerHotkey(Hotkey hotkey);
+
+    /**
+     * Unregisters a hotkey with the given id.
+     * @param id The id of the hotkey to be unregistered.
+     * @return If the unregistration was successful.
+     */
+    boolean unregisterHotkey(int id);
+}

src/model/InputEmulator.java

+package model;
+
+public interface InputEmulator {
+    /**
+     * Sends a given key to be emulated.
+     * @param keyCode The virtual keycode of the key.
+     * @param release True if the key is to be a key release input.
+     */
+    void sendKey(int keyCode, boolean release);
+}