Make GUI window key bindings configurable

[o-sdn-o]

Changes

• Make text anti-aliasing enabled by default.
• Make GUI window key bindings configurable.
• Introduce Drop and DropIfRepeats actions.

  Action	Description
  Drop	Drop all events for the specified key combination. No further processing.
  DropIfRepeats	Drop Key Repeat events for the specified key combination. This binding should be specified before the main action for the key combination.

  <config>
    <gui>
      <hotkeys key*>
        <key="Alt+Enter" action=DropIfRepeats/>           <!-- Don't repeat the Toggle fullscreen mode. -->
        <key="Alt+Enter" action=ToggleFullscreenMode/>    <!-- Toggle fullscreen mode. -->
      </hotkeys>
    </gui>
  </config>