added simple parser to allow
	-set time for attenuation duration with
		-t <time in sec>

	-set attenuation stregth in dB with
		-a <dB>

	-set attenuation form with
		-f <ramp|sine|triangle>

Signed-off-by: Stefan Venz <ikstream86@gmail.com>
added command line options to test -h output

Signed-off-by: Stefan Venz <ikstream86@gmail.com>