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

# -*- coding: utf-8 -*-

__all__ = [
	'basicapplication',
	'fife_compat',
	'fife_timer',
	'fife_utils',
	'fifelog',
	'filebrowser',
	'pythonize',
	'savers',
	'soundmanager',
	'fife_math'
]