Moved the SoundManager and the 2D math function (helpers) from the shooter demo to the fife extensions. Fixed fife_timer as it didn't work in the first place. Modified the SoundManager to use the now working fife_timer and removed the Timer class from the shooter demo entirely

<Panel title="Help">
	<ScrollArea min_size="300,400">
		<TextBox name="helpText"/>
	</ScrollArea>
	<Button name="closeButton" text="Close"/>
</Panel>