Modified PreferencesWindow.xib, FUCommentNotificationWindowController, FUSpeechManager and FUComment to implement fullscreen.
Note that an 'align' attribute was added to thumbnail <img> tag.
Implemented volume slider and removed mute functionality instead.
Fixed the issue that comments with thumbnail could not be displayed properly in recent menu.
Fixed the issue that default volume was not set to speech synthesizers.
Incremented version number.