spgram: adding test for different window types
spgram: adding test for different window types

wangning223/liquid-dsp,wangning223/liquid-dsp,JayKickliter/liquid-dsp,jgaeddert/liquid-dsp,jgaeddert/liquid-dsp,wangning223/liquid-dsp,JayKickliter/liquid-dsp,JayKickliter/liquid-dsp,jgaeddert/liquid-dsp,wangning223/liquid-dsp,JayKickliter/liquid-dsp,wangning223/liquid-dsp,jgaeddert/liquid-dsp,JayKickliter/liquid-dsp,jgaeddert/liquid-dsp