Add API key authentication.

We don't have any sensitive data, but we do access the file system. On
the off chance that some phishing website decides to try to use
Liberation as an attack vector, prevent access to the API by
unauthorized applications. An API key is generated at each program start
and passed to the front end via the QWebChannel.

qt_ui/windows/QLiberationWindow.py

@@ -21,6 +21,7 @@ import qt_ui.uiconstants as CONST
 from game import Game, VERSION, persistency
 from game.debriefing import Debriefing
 from game.server import EventStream
+from game.server.security import ApiKeyManager
 from qt_ui import liberation_install
 from qt_ui.dialogs import Dialog
 from qt_ui.models import GameModel
@@ -88,6 +89,8 @@ class QLiberationWindow(QMainWindow):
         else:
             self.onGameGenerated(self.game)
 
+        logging.debug(f"API Key: {ApiKeyManager.KEY}")
+
     def initUi(self):
         hbox = QSplitter(Qt.Horizontal)
         vbox = QSplitter(Qt.Vertical)